Polymer compositions of dihydroxyacetone and uses thereof

ABSTRACT

The present disclosure provides injectable synthetic and biodegradable polymeric biomaterials that effectively prevent seroma, a common postoperative complication following ablative and reconstructive surgeries. Provided biomaterials include physically crosslinked hydrogels that are thixotropic, display rapid chain relaxation, are easily extruded through narrow gauge needles, biodegrade into inert products, are well tolerated by soft tissues, and effectively prevent seroma in a radical breast mastectomy animal model.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119(e) to U.S.provisional application U.S. Ser. No. 61/110,734, filed Nov. 3, 2008,the entire contents of which are hereby incorporated by reference.

GOVERNMENT SUPPORT

This invention was made with United States Government support undergrant CBET-0642509 awarded by the National Science Foundation. TheUnited States Government has certain rights in the invention.

BACKGROUND OF THE INVENTION

Seromas are a postoperative accumulations of serous fluid and are one ofthe most common complications in surgery today. Conventional woundmanagement techniques are commonly applied when a seroma becomes aclinical concern. Placement of a seroma catheter or additional drain, aswell as repeated or serial drainage of a seroma, may be required. Suchcomplications result in a significant amount of lost income to patients,as well as expenses to insurers and physicians who have to care forthese patients that require serial drainage. Such complications alsodelay wound healing, may entail additional surgical procedures, andultimately delay the patient's return to work and routine functionalactivity. Seroma management can also be costly and, further, can placehealth care workers to additional needle exposure risks and relatedoutcomes.

Several approaches to reduce seroma formation have been investigated.Surgical techniques, such as collapsing the seroma cavity with sutures,do not consistently and adequately eliminate seroma formation (Chilson,supra; Odwyer, P. J., O'Higgins, N. J., James, A. G. (1991); “Effect ofclosing dead space on incidence of seroma after mastectomy.” SurgGynecol Obstet 172, 55-56; Covency, E. C., O'Dwyer, P. J., Geraghty, J.G., O'Higgins, N.J. (1993) “Effect of closing dead space on seromaformation after mastectomy—a prospective randomized clinical trial.” EurJ Sur Oncol 19, 143-146). Other methods, such as sclerotherapy (Tekin,E., Kocdor, M. A., Saydam, S., Bora, S., Harmancioglu, O. (2001) “Seromaprevention by using Corynebacterium parvum in a rat mastectomy model.”Eur Surg Res 33, 245-248; Rice, D. C., et al. (2000) “Intraoperativetopical tetracycline sclerotherapy following mastectomy: A prospective,randomized trial.” J Surg Oncol 73, 224-227), compression dressings(O'hea, B. J., Ho, M. N., Petrek, J. A. (1999) “External compressiondressing versus standard dressing after axillary lymphadenectomy.” Am JSurg 177, 450-453), and biological adhesives, particularly fibrin glue(Lindsey, W. H., Masterson, T. M., Spotnitz, W. D., Wilhelm, M. C.,Morgan, R. F. (1990) “Seroma prevention using fibrin glue in a ratmastectomy model.” Arch Surg 125, 305-307; Harada, R. N., Pressler, V.M., McNamara, J. J. (1992) “Fibrin glue reduces seroma formation in therat after mastectomy.” Surg Gynecol Obstet 175, 450-454; Wang, J. Y., etal. (1996) “Seroma prevention in a rat mastectomy model: Use of alight-activated fibrin sealant.” Ann Plast Surg 37, 400-405; Sanders, R.P., et al. (1996) “Effect of fibrinogen and thrombin concentrations onmastectomy seroma prevention.” J Surg Res 61, 65-70; Carless, P. A.,Henry, D. A. (2006) “Systematic review and meta-analysis of the use offibrin sealant to prevent seroma formation after breast cancer surgery.”Brit J Surg 93, 810-819), have not significantly decreased the clinicalincidence of seroma formation. The current lack of effective methodsavailable to medical practitioners dealing with seromas highlights theneed for new methods for the prevention or treatment of seromas.

SUMMARY OF THE INVENTION

The present disclosure provides compositions of polydihydroxyacetone(pDHA) and methods of using the same. In some embodiments, providedcompositions are copolymers of pDHA. In certain embodiments, providedcopolymers are useful for treating and/or preventing seromas. In certainembodiments, provided copolymers are useful for treating and/orpreventing post-operative tissue adhesion. In some embodiments, providedcopolymers are useful for achieving hemostasis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts scanning electron micrographs (SEMs) of lyophilizedMPEG-pDHA gels. (a) 5000-3000, (b) 5000-5000, (c) 5000-7000. Increasingthe pDHA chain length reduces the hydrogel porosity.

FIG. 2 depicts characterization data for MPEG-pDHA. (a) Viscosityreadings demonstrate the MPEG-pDHA hydrogel thixotropic behavior (1%strain, 28° C.). (b) An example of MPEG-pDHA 5000-5000 extruded from a26 G needle. (c) G′ and G″ readings as obtained from frequency sweepexperiments on the MPEG-pDHA gels (1% strain, 28° C.).

FIG. 3 depicts additional characterization data for MPEG-pDHA. (a)Kinetics of weight loss of MPEG-pDHA hydrogels in water show 100%degradation within one day. (b)¹H NMR of hydrolyzed MPEG-pDHA productsin D₂O, indicate that the end products are MPEG and monomeric DHA.

FIG. 4 depicts seroma volumes from a rat mastectomy model. The untreatedcontrols displayed a mean seroma volume of 2.28±0.55 mL (n=6). MPEG-pDHA5000-3000 treated rats displayed a mean seroma volume of 0.044±0.017 mL(n=9, p<0.01). MPEG-pDHA 5000-5000 treated rats displayed a mean seromavolume of 2.53±0.70 (n=8). MPEG-pDHA 5000-7000 treated rats had a meanseroma volume of 1.93±0.60 (n=8). Treatment with both hydrolyzed andlysine-treated MPEG-pDHA did not result in statistically significantreduction in seroma volume relative to untreated control (2.6±1.16, n=6,and 1.41±0.63, n=6, respectively)

FIG. 5 depicts light microscopic appearance of surgical sites at 7 days(a) control, (b) MPEG-pDHA 5000-3000, (c) MPEG-pDHA 5000-5000, and (d)MPEG-pDHA 5000-7000. The sections show early granulation tissue adjacentto surgical site, which is the clear space at the bottom of all images.H&E stain, 100× magnification.

FIG. 6 depicts a synthetic route to poly(MPEG-b-2-oxypropylenecarbonate), MPEG-pDHA (VII). (a) Trimethyl orthoformate/p-toluenesulfonic acid, (b) ethylchloroformate/triethylamine, (c) stannousoctoate/100° C., (d) trifluoroacetic acid/H₂O. Nomenclature: (I) DHA;(II) DHA dimer; (III) 2,2-dimethoxy-1,3-propane diol; (IV)2,2-dimethoxy-1,3-propylene carbonate; (V) Monomethoxy-PEG (MPEG); (VI)poly(MPEG-b-2,2-dimethoxy-1,3-propylene carbonate); (VII)poly(MPEG-b-2-oxypropylene carbonate) (pDHA) (Zawaneh, infra).Reproduced with permission from Biomacromolecules 2006, 7, 3245-3251.Copyright 2006 American Chemical Society.

FIG. 7 depicts a frequency sweep experiment on a MPEG-pDHA hydrogel at a1% strain (a) 28° C., (b) 37° C. The materials display a trend ofdecreasing viscosities with increasing shear rates (thixotropicbehavior). Increasing the temperature has no effect on the hydrogelviscosity.

FIG. 8 depicts a frequency sweep experiment on a MPEG-pDHA hydrogel at28° C. and a 1% strain. (a) 5000-3000, (b) 5000-5000, (c) 5000-7000. G′values are greater than G″ values across the entire frequency range, acharacteristic typical of elastic hydrogels. G′ and G″ values are usedto calculate gel entanglement density.

FIG. 9 depicts a frequency sweep experiment on a MPEG-pDHA gel at 37° C.and a 1% strain. (a) 5000-3000, (b) 5000-5000, (c) 5000-7000. G′ valuesare greater than G″ values across the entire frequency range, acharacteristic typical of elastic hydrogels. G′ and G″ values are usedto calculate gel entanglement density.

FIG. 10 depicts relaxation modulus G(t) results on a MPEG-pDHA gel at a1% strain. (a) 28° C., (b) 37° C. These results are used to calculatethe gel relaxation kinetics.

FIG. 11 depicts a ¹H NMR of (a) MPEG and (b) DHA in D₂O*. These spectraand FIG. 3 b indicate the degradation products for pDHA hydrogels areMPEG and monomeric DHA.

FIG. 12 depicts a photograph of surgical cavity showing residualMPEG-pDHA 24 hours post surgery.

FIG. 13 depicts a photograph of surgical cavity showing the absence ofMPEG-pDHA 72 hours post surgery.

DEFINITIONS

Compounds of this invention include those described generally above, andare further illustrated by the classes, subclasses, and speciesdisclosed herein. As used herein, the following definitions shall applyunless otherwise indicated. For purposes of this invention, the chemicalelements are identified in accordance with the Periodic Table of theElements, CAS version, Handbook of Chemistry and Physics, 75th Ed.Additionally, general principles of organic chemistry are described inOrganic Chemistry, Thomas Sorrell, University Science Books, Sausalito:1999, and March's Advanced Organic Chemistry, 5^(th) Ed., Ed.: Smith, M.B. and March, J., John Wiley & Sons, New York: 2001, the entire contentsof which are hereby incorporated by reference.

The term “acyl,” used alone or a part of a larger moiety, refers togroups formed by removing a hydroxy group from a carboxylic acid. Suchacyl groups include —C(═O)aliphatic, —C(═O)aryl, —C(═O)heteroaliphatic,or —C(═O)heteroaryl groups. Exemplary acyl groups include, withoutlimitation, —C(═O)Me, —C(═O)Et, —C(═O)i-Pr, and —C(═O)CH₂F.

The term “aliphatic” or “aliphatic group”, as used herein, means astraight-chain (i.e., unbranched) or branched, substituted orunsubstituted hydrocarbon chain that is completely saturated or thatcontains one or more units of unsaturation, or a monocyclic hydrocarbonor bicyclic hydrocarbon that is completely saturated or that containsone or more units of unsaturation, but which is not aromatic, that has asingle point of attachment to the rest of the molecule. Unless otherwisespecified, aliphatic groups contain 1-6 aliphatic carbon atoms. In someembodiments, aliphatic groups contain 1-5 aliphatic carbon atoms. Insome embodiments, aliphatic groups contain 1-4 aliphatic carbon atoms.In some embodiments, aliphatic groups contain 1-3 aliphatic carbonatoms, and in some embodiments, aliphatic groups contain 1-2 aliphaticcarbon atoms. In some embodiments, “cycloaliphatic” (or “carbocycle” or“cycloalkyl”) refers to a monocyclic C₃-C₆ hydrocarbon that iscompletely saturated or that contains one or more units of unsaturation,but which is not aromatic, that has a single point of attachment to therest of the molecule. Suitable aliphatic groups include, but are notlimited to, linear or branched, substituted or unsubstituted alkyl,alkenyl, alkynyl groups and hybrids thereof such as (cycloalkyl)alkyl,(cycloalkenyl)alkyl or (cycloalkyl)alkenyl.

The term “heteroaliphatic,” as used herein, refers to aliphatic groupswherein one or more carbon atoms are independently replaced by one ormore atoms selected from the group consisting of oxygen, sulfur,nitrogen, phosphorus, or silicon. In certain embodiments, one to sixcarbon atoms are independently replaced by one or more of oxygen,sulfur, nitrogen, or phosphorus. Heteroaliphatic groups may besubstituted or unsubstituted, branched or unbranched, cyclic or acyclic,and include saturated, unsaturated or partially unsaturated groups.

The term “unsaturated,” as used herein, means that a moiety has one ormore units of unsaturation.

The term “alkylene” refers to a bivalent alkyl group. An “alkylenechain” is a polymethylene group, i.e., —(CH₂)_(n)—, wherein n is apositive integer, preferably from 1 to 6, from 1 to 4, from 1 to 3, from1 to 2, or from 2 to 3. A substituted alkylene chain is a polymethylenegroup in which one or more methylene hydrogen atoms are replaced with asubstituent. Suitable substituents include those described below for asubstituted aliphatic group.

The term “aryl” used alone or as part of a larger moiety as in“aralkyl,” “aralkoxy,” or “aryloxyalkyl,” refers to monocyclic orbicyclic ring systems having a total of five to fourteen ring members,wherein at least one ring in the system is aromatic and wherein eachring in the system contains 3 to 7 ring members. The term “aryl” may beused interchangeably with the term “aryl ring.”

The term “aryl” used alone or as part of a larger moiety as in“aralkyl,” “aralkoxy,” or “aryloxyalkyl,” refers to monocyclic andbicyclic ring systems having a total of five to 10 ring members, whereinat least one ring in the system is aromatic and wherein each ring in thesystem contains three to seven ring members. The term “aryl” may be usedinterchangeably with the term “aryl ring”. In certain embodiments of thepresent invention, “aryl” refers to an aromatic ring system whichincludes, but not limited to, phenyl, biphenyl, naphthyl, anthracyl andthe like, which may bear one or more substituents. Also included withinthe scope of the term “aryl,” as it is used herein, is a group in whichan aromatic ring is fused to one or more non-aromatic rings, such asindanyl, phthalimidyl, naphthimidyl, phenanthridinyl, ortetrahydronaphthyl, and the like.

The terms “heteroaryl” and “heteroar-,” used alone or as part of alarger moiety, e.g., “heteroaralkyl,” or “heteroaralkoxy,” refer togroups having 5 to 10 ring atoms, preferably 5, 6, or 9 ring atoms;having 6, 10, or 14 π electrons shared in a cyclic array; and having, inaddition to carbon atoms, from one to five heteroatoms. The term“heteroatom” refers to nitrogen, oxygen, or sulfur, and includes anyoxidized form of nitrogen or sulfur, and any quaternized form of a basicnitrogen. Heteroaryl groups include, without limitation, thienyl,furanyl, pyrrolyl, imidazolyl, pyrazolyl, triazolyl, tetrazolyl,oxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, isothiazolyl,thiadiazolyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolizinyl,purinyl, naphthyridinyl, and pteridinyl. The terms “heteroaryl” and“heteroar-”, as used herein, also include groups in which aheteroaromatic ring is fused to one or more aryl, cycloaliphatic, orheterocyclyl rings, where the radical or point of attachment is on theheteroaromatic ring. Nonlimiting examples include indolyl, isoindolyl,benzothienyl, benzofuranyl, dibenzofuranyl, indazolyl, benzimidazolyl,benzthiazolyl, quinolyl, isoquinolyl, cinnolinyl, phthalazinyl,quinazolinyl, quinoxalinyl, 4H-quinolizinyl, carbazolyl, acridinyl,phenazinyl, phenothiazinyl, phenoxazinyl, tetrahydroquinolinyl,tetrahydroisoquinolinyl, and pyrido[2,3-b]-1,4-oxazin-3(4H)-one. Aheteroaryl group may be mono- or bicyclic. The term “heteroaryl” may beused interchangeably with the terms “heteroaryl ring,” “heteroarylgroup,” or “heteroaromatic,” any of which terms include rings that areoptionally substituted. The term “heteroaralkyl” refers to an alkylgroup substituted by a heteroaryl, wherein the alkyl and heteroarylportions independently are optionally substituted.

As used herein, the terms “heterocycle,” “heterocyclyl,” “heterocyclicradical,” and “heterocyclic ring” are used interchangeably and refer toa stable 5- to 7-membered monocyclic or 7-10-membered bicyclicheterocyclic moiety that is either saturated or partially unsaturated,and having, in addition to carbon atoms, one or more, preferably one tofour, heteroatoms, as defined above. When used in reference to a ringatom of a heterocycle, the term “nitrogen” includes a substitutednitrogen. As an example, in a saturated or partially unsaturated ringhaving 0-3 heteroatoms selected from oxygen, sulfur or nitrogen, thenitrogen may be N (as in 3,4-dihydro-2H-pyrrolyl), NH (as inpyrrolidinyl), or ⁺NR (as in N-substituted pyrrolidinyl).

A heterocyclic ring can be attached to its pendant group at anyheteroatom or carbon atom that results in a stable structure and any ofthe ring atoms can be optionally substituted. Examples of such saturatedor partially unsaturated heterocyclic radicals include, withoutlimitation, tetrahydrofuranyl, tetrahydrothiophenyl pyrrolidinyl,piperidinyl, pyrrolinyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl,decahydroquinolinyl, oxazolidinyl, piperazinyl, dioxanyl, dioxolanyl,diazepinyl, oxazepinyl, thiazepinyl, morpholinyl, and quinuclidinyl. Theterms “heterocycle,” “heterocyclyl,” “heterocyclyl ring,” “heterocyclicgroup,” “heterocyclic moiety,” and “heterocyclic radical,” are usedinterchangeably herein, and also include groups in which a heterocyclylring is fused to one or more aryl, heteroaryl, or cycloaliphatic rings,such as indolinyl, 3H-indolyl, chromanyl, phenanthridinyl, ortetrahydroquinolinyl, where the radical or point of attachment is on theheterocyclyl ring. A heterocyclyl group may be mono- or bicyclic. Theterm “heterocyclylalkyl” refers to an alkyl group substituted by aheterocyclyl, wherein the alkyl and heterocyclyl portions independentlyare optionally substituted.

As used herein, the term “partially unsaturated” refers to a ring moietythat includes at least one double or triple bond. The term “partiallyunsaturated” is intended to encompass rings having multiple sites ofunsaturation, but is not intended to include aryl or heteroarylmoieties, as herein defined.

As described herein, compounds of the invention may contain “optionallysubstituted” moieties. In general, the term “substituted”, whetherpreceded by the term “optionally” or not, means that one or morehydrogens of the designated moiety are replaced with a suitablesubstituent. Unless otherwise indicated, an “optionally substituted”group may have a suitable substituent at each substitutable position ofthe group, and when more than one position in any given structure may besubstituted with more than one substituent selected from a specifiedgroup, the substituent may be either the same or different at everyposition. Combinations of substituents envisioned by this invention arepreferably those that result in the formation of stable or chemicallyfeasible compounds. The term “stable”, as used herein, refers tocompounds that are not substantially altered when subjected toconditions to allow for their production, detection, and, in certainembodiments, their recovery, purification, and use for one or more ofthe purposes disclosed herein.

Suitable monovalent substituents on a substitutable carbon atom of an“optionally substituted” group are independently halogen;—(CH₂)₀₋₄R^(∘); —(CH₂)₀₋₄OR^(∘); —O—(CH₂)₀₋₄C(O)OR^(∘);—(CH₂)₀₋₄CH(OR^(∘))₂; —(CH₂)₀₋₄SR^(∘); —(CH₂)₀₋₄Ph, which may besubstituted with R^(∘); —(CH₂)₀₋₄O(CH₂)₀₋₁Ph which may be substitutedwith R^(∘); —CH═CHPh, which may be substituted with R^(∘); —NO₂; —CN;—N₃—(CH₂)₀₋₄N(R^(∘))₂; —(CH₂)₀₋₄N(R^(∘))C(O)R^(∘); —N(R^(∘))C(S)R^(∘);—(CH₂)₀₋₄N(R^(∘))C(O)NR^(∘) ₂; —N(R^(∘))C(S)NR^(∘) ₂;—(CH₂)₀₋₄N(R^(∘))C(O)OR^(∘); —N(R^(∘))N(R^(∘))C(O)R^(∘);—N(R^(∘))N(R^(∘))C(O)NR^(∘) ₂; —N(R^(∘))N(R^(∘))C(O)OR^(∘);—(CH₂)₀₋₄C(O)R^(∘); —C(S)R^(∘); —(CH₂)₀₋₄C(O)OR^(∘);—(CH₂)₀₋₄C(O)N(R^(∘))₂; —(CH₂)₀₋₄C(O)SR^(∘); —(CH₂)₀₋₄C(O)OSiR^(∘) ₃;—(CH₂)₀₋₄OC(O)R^(∘); —OC(O)(CH₂)₀₋₄SR^(∘), SC(S)SR^(∘);—(CH₂)₀₋₄SC(O)R^(∘); —(CH₂)₀₋₄C(O)NR^(∘) ₂; —C(S)NR^(∘) ₂; —C(S)SR^(∘);—SC(S)SR^(∘), —(CH₂)₀₋₄OC(O)NR^(∘) ₂; —C(O)N(OR^(∘))R^(∘);—C(O)C(O)R^(∘); —C(O)CH₂C(O)R^(∘); —C(NOR^(∘))R^(∘); —(CH₂)₀₋₄SSR^(∘);—(CH₂)₀₋₄S(O)₂R^(∘); —(CH₂)₀₋₄S(O)₂OR^(∘); —(CH₂)₀₋₄OS(O)₂R^(∘);—S(O)₂NR^(∘) ₂; —(CH₂)₀₋₄S(O)R^(∘); —N(R^(∘))S(O)₂NR^(∘) ₂;—N(R^(∘))S(O)₂R^(∘); —N(OR^(∘))R^(∘); —C(NH)NR^(∘) ₂; —P(O)₂R^(∘);—P(O)R^(∘) ₂; —OP(O)R^(∘) ₂; —OP(O)(OR^(∘))₂; SiR^(∘) ₃; —(C₁₋₄ straightor branched)alkylene)O—N(R^(∘))₂; or —(C₁₋₄ straight or branched)alkylene)C(O)O—N(R^(∘))₂, wherein each R^(∘) may be substituted asdefined below and is independently hydrogen, C₁₋₈ aliphatic, —CH₂Ph,—O(CH₂)₀₋₁Ph, or a 5-6-membered saturated, partially unsaturated, oraryl ring having 0-4 heteroatoms independently selected from nitrogen,oxygen, or sulfur, or, notwithstanding the definition above, twoindependent occurrences of R^(∘), taken together with their interveningatom(s), form a 3- to 12-membered saturated, partially unsaturated, oraryl mono- or polycyclic ring having 0-4 heteroatoms independentlyselected from nitrogen, oxygen, or sulfur, which may be substituted asdefined below.

Suitable monovalent substituents on R^(∘) (or the ring formed by takingtwo independent occurrences of R^(∘) together with their interveningatoms), are independently halogen, —(CH₂)₀₋₂R^(•), -(haloR^(•)),—(CH₂)₀₋₂OH, —(CH₂)₀₋₂OR^(•), —(CH₂)₀₋₂CH(OR^(•))₂; —O(haloR^(•)), —CN,—N₃, —(CH₂)₀₋₂C(O)R^(•), —(CH₂)₀₋₂C(O)OH, —(CH₂)₀₋₂C(O)OR^(•),—(CH₂)₀₋₄C(O)N(R^(∘))₂; —(CH₂)₀₋₂SR^(•), —(CH₂)₀₋₂SH, —(CH₂)₀₋₂NH₂,—(CH₂)₀₋₂NHR^(•), —(CH₂)₀₋₂NR^(•) ₂, —NO₂, —SiR^(•) ₃, —OSiR^(•) ₃,—C(O)SR^(•), —(C₁₋₄ straight or branched alkylene)C(O)OR^(•), or—SSR^(•) wherein each R^(•) is unsubstituted or where preceded by “halo”is substituted only with one or more halogens, and is independentlyselected from C₁₋₄ aliphatic, —CH₂Ph, —O(CH₂)₀₋₁Ph, or a 5- to6-membered saturated, partially unsaturated, or aryl ring having 0-4heteroatoms independently selected from nitrogen, oxygen, or sulfur.Suitable divalent substituents on a saturated carbon atom of R^(∘)include ═O and ═S.

Suitable divalent substituents on a saturated carbon atom of an“optionally substituted” group include the following: ═O, ═S, ═NNR*₂,═NNHC(O)R*, ═NNHC(O)OR*, ═NNHS(O)₂R*, ═NR*, ═NOR*, —O(C(R*₂))₂₋₃O—, or—S(C(R*₂))₂₋₃S—, wherein each independent occurrence of R* is selectedfrom hydrogen, C₁₋₆ aliphatic which may be substituted as defined below,or an unsubstituted 5-6-membered saturated, partially unsaturated, oraryl ring having 0-4 heteroatoms independently selected from nitrogen,oxygen, or sulfur. Suitable divalent substituents that are bound tovicinal substitutable carbons of an “optionally substituted” groupinclude: —O(CR*₂)₂₋₃O—, wherein each independent occurrence of R* isselected from hydrogen, C₁₋₆ aliphatic which may be substituted asdefined below, or an unsubstituted 5- to 6-membered saturated, partiallyunsaturated, or aryl ring having 0-4 heteroatoms independently selectedfrom nitrogen, oxygen, or sulfur.

Suitable substituents on the aliphatic group of R* include halogen,—R^(•), -(haloR^(•)), —OH, —OR^(•), —O(haloR^(•)), —CN, —C(O)OH,—C(O)OR^(•), —NH₂, —NHR^(•), —NR^(•) ₂, or —NO₂, wherein each R^(•) isunsubstituted or where preceded by “halo” is substituted only with oneor more halogens, and is independently C₁₋₄ aliphatic, —CH₂Ph,—O(CH₂)₀₋₁ Ph, or a 5- to 6-membered saturated, partially unsaturated,or aryl ring having 0-4 heteroatoms independently selected fromnitrogen, oxygen, or sulfur.

Suitable substituents on a substitutable nitrogen of an “optionallysubstituted” group include —R^(†), —NR^(†) ₂, —C(O)R^(†), —C(O)OR^(†),—C(O)C(O)R^(†), —C(O)CH₂C(O)R^(†), —S(O)₂R^(†), —S(O)₂NR^(†) ₂,—C(S)NR^(†) ₂, —C(NH)NR^(†) ₂, or —N(R^(†))S(O)₂R^(†); wherein eachR^(†) is independently hydrogen, C₁₋₆ aliphatic which may be substitutedas defined below, unsubstituted —OPh, or an unsubstituted 5- to6-membered saturated, partially unsaturated, or aryl ring having 0-4heteroatoms independently selected from nitrogen, oxygen, or sulfur, or,notwithstanding the definition above, two independent occurrences ofR^(†), taken together with their intervening atom(s) form anunsubstituted 3- to 12-membered saturated, partially unsaturated, oraryl mono- or bicyclic ring having 0-4 heteroatoms independentlyselected from nitrogen, oxygen, or sulfur.

Suitable substituents on the aliphatic group of R^(†) are independentlyhalogen, —R^(•), -(haloR^(•)), —OH, —OR^(•), —P(haloR^(•)), —CN,—C(O)OH, —C(O)OR^(•), —NH₂, —NHR^(•), —NR^(•) ₂, or —NO₂, wherein eachR^(•) is unsubstituted or where preceded by “halo” is substituted onlywith one or more halogens, and is independently C₁₋₄ aliphatic, —CH₂Ph,—O(CH₂)₀₋₁Ph, or a 5- to 6-membered saturated, partially unsaturated, oraryl ring having 0-4 heteroatoms independently selected from nitrogen,oxygen, or sulfur.

The term “carbohydrate” refers to a sugar or polymer of sugars. Theterms “saccharide”, “polysaccharide”, “carbohydrate”, and“oligosaccharide”, may be used interchangeably. Most carbohydrates arealdehydes or ketones with many hydroxyl groups, usually one on eachcarbon atom of the molecule. Carbohydrates generally have the molecularformula C_(n)H_(2n)O_(n). A carbohydrate may be a monosaccharide, adisaccharide, trisaccharide, oligosaccharide, or polysaccharide. Themost basic carbohydrate is a monosaccharide, such as glucose, sucrose,galactose, mannose, ribose, arabinose, xylose, and fructose.Disaccharides are two joined monosaccharides. Exemplary disaccharidesinclude sucrose, maltose, cellobiose, and lactose. Typically, anoligosaccharide includes between three and six monosaccharide units(e.g., raffinose, stachyose), and polysaccharides include six or moremonosaccharide units. Exemplary polysaccharides include starch,glycogen, and cellulose. Carbohydrates may contain modified saccharideunits such as 2′-deoxyribose wherein a hydroxyl group is removed,2′-fluororibose wherein a hydroxyl group is replace with a fluorine, orN-acetylglucosamine, a nitrogen-containing form of glucose. (e.g.,2′-fluororibose, deoxyribose, and hexose). Carbohydrates may exist inmany different forms, for example, conformers, cyclic forms, acyclicforms, stereoisomers, tautomers, anomers, and isomers.

The term “polypeptide,” generally speaking, is a string of at least twoamino acids attached to one another by a peptide bond. In someembodiments, a polypeptide includes at least 3-5 amino acids, each ofwhich is attached to others by way of at least one peptide bond. Thoseof ordinary skill in the art will appreciate that polypeptides sometimesinclude “unnatural” amino acids or other entities that nonetheless arecapable of integrating into a polypeptide chain, optionally. The term“peptide” is generally used to refer to a polypeptide having a length ofless than about 100 amino acids.

As used herein, the phrase “unnatural amino acid” refers to amino acidsnot included in the list of 20 amino acids naturally occurring inproteins. Such amino acids include the D-isomer of any of the 20naturally occurring amino acids. Unnatural amino acids also includehomoserine, ornithine, norleucine, and thyroxine. Other unnatural aminoacids side-chains are well known to one of ordinary skill in the art andinclude unnatural aliphatic side chains. Other unnatural amino acidsinclude modified amino acids, including those that are N-alkylated,cyclized, phosphorylated, acetylated, amidated, azidylated, labelled,and the like. In some embodiments, an unnatural amino acid is aD-isomer. In some embodiments, an unnatural amino acid is a L-isomer.

As used herein, the term “protein” refers to a polypeptide (i.e., astring of at least two amino acids linked to one another by peptidebonds). Proteins may include moieties other than amino acids (e.g., maybe glycoproteins, proteoglycans, etc.) and/or may be otherwise processedor modified. Those of ordinary skill in the art will appreciate that a“protein” can be a complete polypeptide chain as produced by a cell(with or without a signal sequence), or can be a characteristic portionthereof. Those of ordinary skill will appreciate that a protein cansometimes include more than one polypeptide chain, for example linked byone or more disulfide bonds or associated by other means. Polypeptidesmay contain L-amino acids, D-amino acids, or both and may contain any ofa variety of amino acid modifications or analogs known in the art.Useful modifications include, e.g., terminal acetylation, amidation,etc. In some embodiments, proteins may comprise natural amino acids,non-natural amino acids, synthetic amino acids, and combinationsthereof.

The term “suitable organic group,” as used herein, refers to a protein,peptide, carbohydrate, aliphatic, aryl, heteroaliphatic, heteroaryl, oracyl group.

As used herein, the term “polyol” refers to compounds with multiplehydroxyl functional groups. In some embodiments, a polyol is a diol,triol, or tetrol. In some embodiments, a polyol is an alkylene glycol.In some embodiments, a polyol is an alkylene triol.

As used herein, the term “hydrogel” refers to a polymeric material,typically a network or matrix of polymer chains, capable of swelling inwater or becoming swollen with water. Such polymeric material alreadyswollen or partially swollen with water may also be called a hydrogel. Ahydrogel network or matrix may or may not be cross-linked, andcross-linked materials may be physically and/or chemically cross-linked.Hydrogels also include polymeric materials that are water swellableand/or water swelled. A hydrogel may exist in various states ofhydration. In some embodiments, a hydrogel is unhydrated. In someembodiments, a hydrogel is partially hydrated. In some embodiments, ahydrogel is fully hydrated. In certain embodiments, a hydrogel may bedescribed as being swollen with water. In certain embodiments, ahydrogel may be described as being water swellable.

As used herein, the term “seroma” refers to an accumulation of serousserum in a wound bed or surgical site. While a seroma may be infected orcomprise infected tissue, a seroma does not necessarily involve thepresence of white blood cells, bacteria, and the breakdown products ofboth.

As used herein, the term “hemostasis” refers to the action of stoppingor reducing bleeding (e.g., of or in a tissue). The tissue may be anybiological tissue. In some embodiments, the tissue is living animaltissue. In some embodiments, the tissue is in and/or around a wound bed.In some embodiments, the tissue is in and/or around a surgical site.

As used herein, the term “surgical site” refers to the tissues of asurgical patient adjacent to an actual or intended surgical actionduring or subsequent to a surgery. In some embodiments, a surgical siteis a skin surface location at which surgery is being or has beenconducted. A surgical site includes the intended site for surgicalincision as well as wounds to the skin, such as puncture wounds byobjects. In some embodiments, a surgical site includes a peripheral areaextending from immediately adjacent the surgical site up to about 30 cmfrom the surgical site. In some embodiments, a surgical site includes aperipheral area extending from about 3 cm to about 30 cm from thesurgical site.

The term “incision” or “surgical incision” refers to any surgicalpenetration which extends beyond the epidermal or dermal layer of apatient's skin and includes, by way of example, incisions or puncturesmade by needles, knives (including surgical knives and surgical cauteryknives), medical lasers, trocars, and punctures (e.g., those resultingfrom IV, blood transfusion/donation, vaccine inoculation, medicamentinjections, hemodialysis, etc.).

The term “wound” refers to any wound or injury, including surgicallycreated wounds and accidental or traumatic wounds, such as compoundfractures, gunshot wounds, knife wounds, pellet wounds, contaminated orinfected wounds. The term “wound bed” may be used interchangeably with“wound.” In some embodiments, a wound includes a peripheral areaextending from immediately adjacent the wound up to about 30 cm from thewound. In some embodiments, a wound includes a peripheral area extendingfrom about 3 cm to about 30 cm from the wound.

As used herein, the term “subject” or “patient” refers to any organismto which a composition of this invention may be administered, e.g., forexperimental, diagnostic, prophylactic, and/or therapeutic purposes.Typical subjects include animals (e.g., mammals such as mice, rats,dogs, cats, rabbits, non-human primates, and humans).

An individual who is “suffering from” a disease, disorder, and/orcondition has been diagnosed with or displays one or more symptoms ofthe disease, disorder, and/or condition.

An individual who is “susceptible to” a disease, disorder, and/orcondition has not been diagnosed with the disease, disorder, and/orcondition. In some embodiments, an individual who is susceptible to adisease, disorder, and/or condition may not exhibit symptoms of thedisease, disorder, and/or condition. In some embodiments, an individualwho is susceptible to a disease, disorder, and/or condition will developthe disease, disorder, and/or condition. In some embodiments, anindividual who is susceptible to a disease, disorder, and/or conditionwill not develop the disease, disorder, and/or condition. In someembodiments, an individual who is susceptible to a disease, disorder,and/or condition is an individual having higher risk (typically based ongenetic predisposition, environmental factors, personal history, orcombinations thereof) of developing a particular disease or disorder, orsymptoms thereof, than is observed in the general population.

The term “treatment” is used herein to characterize a method or processthat is aimed at (1) delaying or preventing the onset of a disease,disorder, and/or condition; (2) slowing down or stopping theprogression, aggravation, or deterioration of one or more symptoms ofthe disease, disorder, and/or condition; (3) bringing aboutameliorations of the symptoms of the disease, disorder, and/orcondition; (4) reducing the severity or incidence of the disease,disorder, and/or condition; and/or (5) curing the disease, disorder,and/or condition. A treatment may be administered prior to the onset ofthe disease, disorder, and/or condition, for a prophylactic orpreventive action. Alternatively or additionally, the treatment may beadministered after initiation of the disease, disorder, and/orcondition, for a therapeutic action.

The term “palliative” refers to treatment that is focused on the reliefof symptoms of a disease and/or side effects of a therapeutic regimen,but is not curative.

As used herein and in the claims, the singular forms “a”, “an”, and“the” include the plural reference unless the context clearly indicatesotherwise. Thus, for example, a reference to “a compound” includes aplurality of such compounds. Similarly, a reference to “a polymer”includes a plurality of such polymers.

The phrase “pharmaceutically acceptable” is employed herein to refer tothose compounds, materials, compositions, and/or dosage forms which are,within the scope of sound medical judgment, suitable for use in contactwith the tissues of human beings and animals without excessive toxicity,irritation, allergic response, or other problem or complication,commensurate with a reasonable benefit/risk ratio.

The phrase “pharmaceutically acceptable carrier” as used herein means apharmaceutically-acceptable material, composition or vehicle, such as aliquid or solid filler, diluent, excipient, or solvent encapsulatingmaterial, involved in carrying or transporting the subject compound.Each carrier must be “acceptable” in the sense of being compatible withthe subject compound and other ingredients of the formulation and notinjurious to the patient. Some examples of materials which can serve aspharmaceutically-acceptable carriers include: sugars, such as lactose,glucose and sucrose; starches, such as corn starch and potato starch;cellulose, and its derivatives, such as sodium carboxymethyl cellulose,ethyl cellulose and cellulose acetate; powdered tragacanth; malt;gelatin; talc; excipients, such as cocoa butter and suppository waxes;oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil,olive oil, corn oil and soybean oil; glycols, such as propylene glycol;polyols, such as glycerin, sorbitol, mannitol and polyethylene glycol;esters, such as ethyl oleate and ethyl laurate; agar; buffering agents,such as magnesium hydroxide and aluminum hydroxide; alginic acid;pyrogen-free water; isotonic saline; Ringer's solution; ethyl alcohol;pH buffered solutions; polyesters, polycarbonates and/or polyanhydrides;and other non-toxic compatible substances employed in pharmaceuticalformulations.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

Polymeric biomaterials have contributed significantly to the advancementof medical and surgical practice over the past few decades. Theirmacromolecular structure can be tailored to provide the appropriatecombination of chemical, physical, and biological properties necessaryfor a range of medical and surgical applications. The rational design ofpolymeric biomaterials has impacted many fields including drug and genedelivery, orthopedics, tissue engineering, ophthalmology, and generalsurgery (Langer, R., Tirrell, D. A. (2004) “Designing materials forbiology and medicine.” Nature 428, 487-492; Putnam, D. (2006) “Polymersfor gene delivery across length scales.” Nature Materials 5, 439-451;Wong, S. Y., Pelet, J. M., Putnam, D. (2007) “Polymer systems for genedelivery-past, present, and future.” Prog Polym Sci 32, 799-837).

The present disclosure encompasses the recognition that polymericbiomaterials can be useful in the treatment of wounds and postoperativesurgical sites. To Applicants' knowledge, there are only two publishedaccounts of synthetic biomaterials for seroma prevention. Silverman etal. reported a photopolymerizable material that effectively reducedseroma in a rat mastectomy model, but no follow on studies have beenreported (Silverman, R. P., et al. (1999) “Transdermal photopolymerizedadhesive for seroma prevention.” Plast Reconstr Surg 103, 531-535).Rubin and co-workers have developed a urethane-based material that showsefficacy in a dog seroma model. However, while the results arepromising, the material requires long cure times and appears to be onlyslowly degradable (Gilbert, T. et al. (2008) “Lysine-derived urethanesurgical adhesive prevents seroma formation in a canine abdominoplastymodel.” Plast. Reconstr. Surg 122, 95-102). Given that seromas causesignificant patient morbidity, it is interesting they have not receivedmore attention from the biomaterials community.

The present disclosure provides, among other things, new surgicalbiomaterials with adjustable physiochemical properties that arebiocompatible, easy to handle and apply, and useful for treatingpostoperative conditions and/or complications. Such materials includecopolymers whose physical and rheological properties can be fine-tunedby adjusting the length of its constituting blocks. In certainembodiments, provided surgical biomaterials are useful in treatingseromas, tissue adhesion, and/or bleeding.

Applicants previously described the successful synthesis andcharacterization of a diblock copolymer, MPEG-pDHA, comprised of amonomethoxy poly(ethylene glycol) (MPEG) block, and a polycarbonate(pDHA) block based on the metabolic intermediate, dihydroxyacetone(DHA). See Zawaneh, P. N., Doody, A. M., Zelikin, A. N., Putnam, D.(2006) “Diblock copolymers based on dihydroxyacetone and ethyleneglycol: Synthesis, characterization, and nanoparticle formulation.”Biomacromolecules 7, 3245-3251; and U.S. Pat. Application PublicationNo. 2008-0194786, the entire contents of each of which are herebyincorporated by reference.

Subsequent work with pDHA copolymers has revealed that such copolymershave medically useful properties. Furthermore, Applicants haveunexpectedly found that at higher concentrations, pDHA copolymers form aphysically cross-linked hydrogel that possesses properties that differfrom non-physically cross-linked, non-hydrogel compositions. In certainembodiments, provided pDHA copolymers are thixotropic. In certainembodiments, provided pDHA copolymers display rapid chain relaxation. Incertain embodiments, provided pDHA copolymers possess high porosity. Incertain embodiments, provided pDHA copolymers possess high watercontent. In certain embodiments, provided pDHA copolymers areinjectable. In certain embodiments, a provided pDHA copolymer is apowder.

Applicants have found that by controlling the concentration andcomposition of provided copolymers, physically cross-linked hydrogelsare formed. In certain embodiments, provided copolymers possessdesirable characteristics (for example, physically entangled networksthat form physical cross-links) for uses as described herein. In someembodiments, such characteristics are not present at low concentrationsof provided copolymers. In some embodiments, characteristics such ashydrogel formation are present at high concentrations of providedcopolymers. In some embodiments, provided copolymer form nanoparticlesat low concentrations.

In some embodiments, the present disclosure provides methods of makingprovided hydrogel compositions.

In certain embodiments, the present disclosure provides copolymerscomprising poly-dihydroxyacetone (pDHA). In some embodiments, providedcopolymers are block copolymers of pDHA. In some embodiments, providedcopolymers are diblock copolymers of pDHA. In some embodiments, providedcopolymers are triblock copolymers of pDHA. In some embodiments,provided copolymers are quadblock copolymers of pDHA. In someembodiments, provided copolymers are multiblock copolymers of pDHA. Insome embodiments, provided copolymers comprise DHA and at least oneother monomer. In some embodiments, provided copolymers comprise DHA andglycerol. In some embodiments, provided copolymers comprise DHA and analkylene glycol. In some embodiments, provided copolymers comprise DHAand PEG. In some embodiments, provided copolymers are PEG-pDHA diblockcopolymers. In some embodiments, a provided pDHA copolymer ispoly(MPEG-b-2-oxypropylene carbonate).

In some embodiments, provided copolymers comprise DHA and a polyol. Insome embodiments, a polyol is selected from the group consisting ofethylene glycol, propylene glycol (i.e., a polymer comprising1,2-propane diol, 2-methyl-1,3-propanediol, or 1,3-propane diol),butylene glycol (i.e., a polymer comprising 1,2-butanediol,1,2-butanediol, or 1,4-butanediol), and a carbohydrate. In someembodiments, a carbohydrate polyol is a cyclic saccharide. In someembodiments, a carbohydrate polyol is a hydrogenated sugar alcohol.

In some embodiments, provided copolymers are terminated with a suitableorganic group. In certain embodiments, an alkylene glycol block of aprovided copolymer is terminated with a suitable organic group. In someembodiments, suitable organic groups are aliphatic, acyl,heteroaliphatic, aryl, or heteroaryl. In some embodiments, a suitableorganic group is a carbohydrate, a protein, or a peptide.

In some embodiments, provided pDHA copolymers are block copolymers. Insome embodiments, provided pDHA copolymers are random copolymers.

In some embodiments, provided copolymers comprise DHA, glycerol, andPEG. In some embodiments, a provided pDHA copolymer comprises a firstblock of PEG and a second block comprising DHA and glycerol. In someembodiments, the second block comprising DHA and glycerol is a blockcopolymer. In some embodiments, the second block comprising DHA andglycerol is a random copolymer.

In certain embodiments, provided pDHA copolymers are poly(alkyleneglycol)-pDHA diblock copolymers. In certain embodiments, provided pDHAcopolymers are poly(ethylene glycol)-pDHA diblock copolymers. In certainembodiments, provided pDHA copolymers are poly(propylene glycol)-pDHAdiblock copolymers. In certain embodiments, provided pDHA copolymers arepoly(glycerol)-pDHA diblock copolymers.

In certain embodiments, a poly(alkylene-glycol) block of a providedcopolymer is linear. In other embodiments, a poly(alkylene-glycol) blockof a provided copolymer is branched. In certain embodiments, a PEG blockof a provided copolymer is branched. In certain embodiments, a PEG blockof a provided copolymer is a comb PEG. In certain embodiments, a PEGblock of a provided copolymer is a star PEG. In some embodiments, abranched PEG block comprises 3 to 200 PEG chains emanating from acentral core group. In some embodiments, a branched PEG block comprises3 to 100 PEG chains emanating from a central core group. In someembodiments, a branched PEG block comprises 3 to 50 PEG chains emanatingfrom a central core group. In some embodiments, a branched PEG blockcomprises 3 to 40 PEG chains emanating from a central core group. Insome embodiments, a branched PEG block comprises 3 to 30 PEG chainsemanating from a central core group. In some embodiments, a branched PEGblock comprises 3 to 20 PEG chains emanating from a central core group.In some embodiments, a branched PEG block comprises 10 PEG chainsemanating from a central core group. In some embodiments, a branched PEGblock comprises 9 PEG chains emanating from a central core group. Insome embodiments, a branched PEG block comprises 8 PEG chains emanatingfrom a central core group. In some embodiments, a branched PEG blockcomprises 7 PEG chains emanating from a central core group. In someembodiments, a branched PEG block comprises 6 PEG chains emanating froma central core group. In some embodiments, a branched PEG blockcomprises 5 PEG chains emanating from a central core group. In someembodiments, a branched PEG block comprises 4 PEG chains emanating froma central core group. In some embodiments, a branched PEG blockcomprises 3 PEG chains emanating from a central core group.

In certain embodiments, a pDHA block of provided copolymers has a M_(w)from about 100 to about 1,000,000 daltons. In certain embodiments, apDHA block of provided copolymers has a M_(w) from about 1,000 to about1,000,000 daltons. In certain embodiments, a pDHA block of providedcopolymers has a M_(w) from about 10,000 to about 1,000,000 daltons. Incertain embodiments, a pDHA block of provided copolymers has a M_(w)from about 100,000 to about 1,000,000 daltons. In certain embodiments, apDHA block of provided copolymers has a M_(w) from about 100 to about100,000 daltons. In certain embodiments, a pDHA block of providedcopolymers has a M_(w) from about 100 to about 50,000 daltons. Incertain embodiments, a pDHA block of provided copolymers has a M_(w)from about 100 to about 10,000 daltons. In certain embodiments, a pDHAblock of provided copolymers has a M_(w) from about 1,000 to about50,000 daltons. In certain embodiments, a pDHA block of providedcopolymers has a M_(w) from about 1,000 to about 10,000 daltons. Incertain embodiments, a pDHA block of provided copolymers has a M_(w)from about 1,000 to about 5,000 daltons. In certain embodiments, a pDHAblock of provided copolymers has a M_(w) from about 2,000 to about 5,000daltons. In certain embodiments, a pDHA block of provided copolymers hasa M_(w) from about 2,000 to about 4,000 daltons. In certain embodiments,a pDHA block of provided copolymers has a M_(w) from about 2,500 toabout 4,000 daltons. In certain embodiments, a pDHA block of providedcopolymers has a M_(w) from about 2,500 to about 3,500 daltons. Incertain embodiments, a pDHA block of provided copolymers has a M_(w) ofabout 3,000 daltons.

In certain embodiments, a non-DHA polyol block of provided copolymershas a M_(w) from about 100 to about 1,000,000 daltons. In certainembodiments, a non-DHA polyol block of provided copolymers has a M_(w)from about 1,000 to about 1,000,000 daltons. In certain embodiments, anon-DHA polyol block of provided copolymers has a M_(w) from about10,000 to about 1,000,000 daltons. In certain embodiments, a non-DHApolyol block of provided copolymers has a M_(w) from about 100,000 toabout 1,000,000 daltons. In certain embodiments, a non-DHA polyol blockof provided copolymers has a M_(w) from about 100 to about 100,000daltons. In certain embodiments, a non-DHA polyol block of providedcopolymers has a M_(w) from about 100 to about 50,000 daltons. Incertain embodiments, a non-DHA polyol block of provided copolymers has aM_(w) from about 100 to about 10,000 daltons. In certain embodiments, anon-DHA polyol block of provided copolymers has a M_(w) from about 1,000to about 50,000 daltons. In certain embodiments, a non-DHA polyol blockof provided copolymers has a M_(w) from about 1,000 to about 10,000daltons. In certain embodiments, a non-DHA polyol block of providedcopolymers has a M_(w) from about 1,000 to about 5,000 daltons. Incertain embodiments, a non-DHA polyol block of provided copolymers has aM_(w) from about 2,000 to about 5,000 daltons. In certain embodiments, anon-DHA polyol block of provided copolymers has a M_(w) from about 3,000to about 6,000 daltons. In certain embodiments, a non-DHA polyol blockof provided copolymers has a M_(w) from about 2,500 to about 4,000daltons. In certain embodiments, a non-DHA polyol block of providedcopolymers has a M_(w) from about 2,500 to about 3,500 daltons. Incertain embodiments, a non-DHA polyol block of provided copolymers has aM_(w) of about 5,000 daltons.

In certain embodiments, a provided copolymer is a hydrogel. In someembodiments, a provided copolymer is not cross-linked. In someembodiments, a provided copolymer is cross-linked. In some embodiments,a provided copolymer has the property of decreasing viscosity withincreasing shear rate. In some embodiments, a provided hydrogel has aweight gain swelling percentage of about 100% to about 2,000%. In someembodiments, a provided hydrogel has a weight gain swelling percentageof about 200% to about 1,000%. In some embodiments, a provided hydrogelhas a weight gain swelling percentage of about 200% to about 800%. Insome embodiments, a provided hydrogel has a weight gain swellingpercentage of about 300% to about 700%. In some embodiments, a providedhydrogel has a weight gain swelling percentage of about 400% to about600%. In some embodiments, a provided hydrogel has a weight gainswelling percentage of about 500% to about 600%.

In some embodiments, a provided copolymer has an entanglement density ofabout 5×10²² m⁻³ to about 5×10²⁶ m⁻³. In some embodiments, a providedcopolymer has an entanglement density of about 5×10²³ m⁻³ to about1×10²⁵ m⁻³. In some embodiments, a provided copolymer has anentanglement density of about 5×10²⁴ m⁻³ to about 5×10²⁵ m⁻³. In someembodiments, a provided copolymer has an entanglement density of about1×10²⁴ m⁻³ to about 5×10²⁴ m⁻³. In some embodiments, a providedcopolymer has an entanglement density of about 5×10²⁴ m⁻³.

In certain embodiments, a provided copolymer has a relaxation time ofabout 30 to about 1000 seconds. In certain embodiments, a providedcopolymer has a relaxation time of about 100 to about 500 seconds. Incertain embodiments, a provided copolymer has a relaxation time of about200 to about 500 seconds. In certain embodiments, a provided copolymerhas a relaxation time of about 200 to about 400 seconds. In certainembodiments, a provided copolymer has a relaxation time of about 200 toabout 350 seconds. In certain embodiments, a provided copolymer has arelaxation time of about 225 to about 275 seconds. In certainembodiments, a provided copolymer has a relaxation time of about 250seconds.

Dihydroxyacetone is known to react with amino acids in the upper layersof the skin to produce a tanning effect. The product of DHA-skin proteinreactions is therefore proteins functionalized with monomeric DHA, notpolymeric DHA. In certain embodiments, provided pDHA copolymers do notcomprise DHA-protein conjugates formed by a Maillard reaction (i.e.,reaction between a reducing sugar and an amino acid).

In certain embodiments, a provided pDHA copolymer is of formula VII-a:

wherein,

-   R¹ and R² are each independently an optionally substituted group    selected from C₁₋₂₀ aliphatic; a 3- to 7-membered saturated or    partially unsaturated monocyclic carbocyclic ring; a 7- to    10-membered saturated or partially unsaturated bicyclic carbocyclic    ring; phenyl; an 8- to 10-membered bicyclic aryl ring; a 3- to    7-membered saturated or partially unsaturated monocyclic    heterocyclic ring having 1-2 heteroatoms independently selected from    nitrogen, oxygen, or sulfur; a 7- to 10-membered saturated or    partially unsaturated bicyclic heterocyclic ring having 1-3    heteroatoms independently selected from nitrogen, oxygen, or sulfur;    an 8- to 10-membered bicyclic aryl ring; a 5- to 6-membered    heteroaryl ring having 1-3 heteroatoms independently selected from    nitrogen, oxygen, or sulfur; or an 8- to 10-membered bicyclic    heteroaryl ring having 1-4 heteroatoms independently selected from    nitrogen, oxygen, or sulfur; and    n and m each independently range from 1 to 2000.

In certain embodiments, R¹ is C₁₋₂₀ aliphatic. In certain embodiments,R¹ is C₁₋₁₀ aliphatic. In certain embodiments, R¹ is C₁₋₆ aliphatic. Incertain embodiments, R¹ is methyl. In some embodiments, R¹ is a suitableorganic group. In some embodiments, R¹ is selected from the groupconsisting of carbohydrates, proteins, and peptides.

In some embodiments, R² is C₁₋₂₀ aliphatic. In certain embodiments, R²is C₁₋₁₀ aliphatic. In certain embodiments, R² is C₁₋₆ aliphatic. Incertain embodiments, R² is methyl.

In some embodiments, n is from 1-2000. In some embodiments, n is from10-1000. In some embodiments, n is from 10-500. In some embodiments, nis from 10-250. In some embodiments, n is from 10-200. In someembodiments, n is from 10-150. In some embodiments, n is from 50-200. Insome embodiments, n is from 75-125. In some embodiments, n is a numbersuch that the total molecular weight of the n bracketed block is fromabout 200 to about 20,000 daltons. In some embodiments, n is a numbersuch that the total molecular weight of the n bracketed block is fromabout 500 to about 10,000 daltons. In some embodiments, n is a numbersuch that the total molecular weight of the n bracketed block is fromabout 1,000 to about 10,000 daltons. In some embodiments, n is a numbersuch that the total molecular weight of the n bracketed block is fromabout 2,000 to about 10,000 daltons. In some embodiments, n is a numbersuch that the total molecular weight of the n bracketed block is fromabout 3,000 to about 6,000 daltons.

In some embodiments, m is from 1-2000. In some embodiments, m is from2-2000. In some embodiments, m is from 5-1000. In some embodiments, m isfrom 5-500. In some embodiments, m is from 5-250. In some embodiments, mis from 5-200. In some embodiments, m is from 5-100. In someembodiments, m is from 15-50. In some embodiments, m is from 20-30. Insome embodiments, m is a number such that the total molecular weight ofthe m bracketed block is from about 200 to about 20,000 daltons. In someembodiments, m is a number such that the total molecular weight of the mbracketed block is from about 500 to about 10,000 daltons. In someembodiments, m is a number such that the total molecular weight of the mbracketed block is from about 1,000 to about 10,000 daltons. In someembodiments, m is a number such that the total molecular weight of the mbracketed block is from about 2,000 to about 8,000 daltons. In someembodiments, m is a number such that the total molecular weight of the mbracketed block is from about 3,000 to about 7,000 daltons. In someembodiments, m is a number such that the total molecular weight of the mbracketed block is from about 4,000 to about 6,000 daltons. In someembodiments, m is a number such that the total molecular weight of the mbracketed block is about 5,000 daltons.

In some embodiments, molecular weights described herein refer to themolecular weight of a single molecule or part of a molecule. In someembodiments, molecular weights described herein refer to the averagemolecular weight in a composition of provided polymers.

In certain embodiments, a provided pDHA copolymer is of formula VII-b:

wherein each of R¹, n, and m are as defined above and described inclasses and subclasses herein.

It will be appreciated that provided pDHA copolymers comprise a ketonegroup that may be protected with a carbonyl protecting group. Forexample, provided polymers can be made using dihydroxyacetone monomerand/or dimer that are chemically protected, e.g., from protecteddihydroxyacetone monomer where the carbonyl group of the monomer isprotected, e.g., from 2,2-di-C₁-C₁₀ alkoxy-propane-1,3-diol, or from2,2-dimethoxy-propane-1,3-diol. Other protected forms of the startingmaterial include those where the carbonyl group of the monomer isprotected with methoxybenzyl, benzyloxy, or allyloxy, or those where thehydroxyl groups of the dimer are protected, e.g., from 2,5-di-C₁-C₁₀alkoxy-2,5-bis(hydroxymethyl)-[1,4]-dioxane. The2,2-dimethoxy-propane-1,3 diol is readily made from combination of DHAmonomer and dimer as described in Ferroni, E. L., et al, J. Org. Chem64, 4943-4945 (1999).

In addition to polymerizing functionalized monomer, provided pDHAcopolymers may be functionalized at the polymer stage. Suchfunctionalization has been previously demonstrated in the art (see forexample U.S. Pat. Application Publication No. 2008-0194786). Forexample, a compound of formula VII-a may be functionalized by one ormore nucleophiles. In certain embodiments, a compound of formula VII-ais treated with an amine and a suitable reducing agent. In someembodiments, the reducing agent is selected from NaBH₄, NaBH₃CN, orNaBH(OCOCH₃)₃.

Thus, in certain embodiments, provided pDHA copolymers are of formulaVIII:

wherein each of R¹, R², n, and m is as defined above and described inclasses and subclasses herein; and

-   R³ and R⁴ are each independently selected from the group consisting    of R⁵, —OR⁵, and —N(R⁵)₂; or:    -   R³ and R⁴ are optionally taken together with their intervening        atoms to form an optionally substituted ring selected from a 3-        to 7-membered saturated or partially unsaturated monocyclic        heterocyclic ring having 1-2 heteroatoms independently selected        from nitrogen, oxygen, or sulfur; or a 7- to 10-membered        saturated or partially unsaturated bicyclic heterocyclic ring        having 1-3 heteroatoms independently selected from nitrogen,        oxygen, or sulfur; and-   each R⁵ is independently hydrogen or an optionally substituted group    selected from C₁₋₂₀ aliphatic; a 3- to 7-membered saturated or    partially unsaturated monocyclic carbocyclic ring; a 7- to    10-membered saturated or partially unsaturated bicyclic carbocyclic    ring; phenyl; an 8- to 10-membered bicyclic aryl ring; a 3- to    7-membered saturated or partially unsaturated monocyclic    heterocyclic ring having 1-2 heteroatoms independently selected from    nitrogen, oxygen, or sulfur; a 7- to 10-membered saturated or    partially unsaturated bicyclic heterocyclic ring having 1-3    heteroatoms independently selected from nitrogen, oxygen, or sulfur;    an 8- to 10-membered bicyclic aryl ring; a 5- to 6-membered    heteroaryl ring having 1-3 heteroatoms independently selected from    nitrogen, oxygen, or sulfur; or an 8- to 10-membered bicyclic    heteroaryl ring having 1-4 heteroatoms independently selected from    nitrogen, oxygen, or sulfur.

In some embodiments, R³ is R⁵. In some embodiments, R³ is —OR⁵. In otherembodiments, R³ is —N(R⁵)₂. In some embodiments, R³ is —N(R⁵)₂, whereineach R⁵ is independently an optionally substituted group selected fromC₁₋₁₀ aliphatic or phenyl. In some embodiments, R³ is—NH(CH₂)₄CH(NH₂)CO₂H.

In some embodiments, R⁴ is R⁵. In some embodiments, R⁴ is —OR⁵. In otherembodiments, R⁴ is —N(R⁵)₂.

In certain embodiments, R³ and R⁴ form a suitable carbonyl protectinggroup. Suitable carbonyl protecting groups are well known in the art andinclude those described in detail in Protecting Groups in OrganicSynthesis, T. W. Greene and P. G. M. Wuts, 3^(rd) edition, John Wiley &Sons, 1999, the entirety of which is incorporated herein by reference.

In some embodiments, R³ and R⁴ are each independently selected from thegroup consisting of R⁵, —OR⁵, and —N(R⁵)₂. In certain embodiments, R³and R⁴ are each —N(R⁵)₂, wherein R⁵ is C₁₋₂₀ aliphatic. In certainembodiments, R³ and R⁴ are each —OR⁵, wherein R⁵ is C₁₋₂₀ aliphatic. Incertain embodiments, R³ and R⁴ are each —OR⁵, wherein R⁵ is C₁₋₁₀aliphatic. In certain embodiments, R³ and R⁴ are each —OR⁵, wherein R⁵is C₁₋₆ aliphatic. In certain embodiments, R³ and R⁴ are each —OR⁵,wherein R⁵ is ethyl. In certain embodiments, R³ and R⁴ are each —OR⁵,wherein R⁵ is methyl.

In some embodiments, R³ and R⁴ are taken together with their interveningatoms to form an optionally substituted spirocyclic 3- to 7-memberedsaturated or partially unsaturated monocyclic heterocyclic ring having1-2 heteroatoms independently selected from nitrogen, oxygen, or sulfur.In some embodiments, R³ and R⁴ are taken together with their interveningatoms to form an optionally substituted 5- to 6-membered cyclic ketal.In some embodiments, R³ and R⁴ are not taken together with theirintervening atoms to form an optionally substituted 5- to 6-memberedcyclic ketal.

In certain embodiments, R⁵ is hydrogen. In certain embodiments, R⁵ isC₁₋₂₀ aliphatic. In certain embodiments, R⁵ is a 3- to 7-memberedsaturated or partially unsaturated monocyclic carbocyclic ring. Incertain embodiments, R⁵ is a 7- to 10-membered saturated or partiallyunsaturated bicyclic carbocyclic ring. In certain embodiments, R⁵ isphenyl. In certain embodiments, R⁵ is an 8- to 10-membered bicyclic arylring. In certain embodiments, R⁵ is a 3- to 7-membered saturated orpartially unsaturated monocyclic heterocyclic ring having 1-2heteroatoms independently selected from nitrogen, oxygen, or sulfur. Incertain embodiments, R⁵ is a 7- to 10-membered saturated or partiallyunsaturated bicyclic heterocyclic ring having 1-3 heteroatomsindependently selected from nitrogen, oxygen, or sulfur. In certainembodiments, R⁵ is an 8- to 10-membered bicyclic aryl ring. In certainembodiments, R⁵ is a 5- to 6-membered heteroaryl ring having 1-3heteroatoms independently selected from nitrogen, oxygen, or sulfur. Incertain embodiments, R⁵ is an 8- to 10-membered bicyclic heteroaryl ringhaving 1-4 heteroatoms independently selected from nitrogen, oxygen, orsulfur.

In certain embodiments, a provided pDHA copolymers are of formula IX:

wherein each of R¹, R², R⁵, n, and m is as defined above and describedin classes and subclasses herein.

In certain embodiments, a provided pDHA copolymer comprises a repeatingsubunit:

wherein each of R³ and R⁴ is as defined above and described in classesand subclasses herein.

In certain embodiments, a provided pDHA copolymer comprises a repeatingsubunit:

wherein R⁵ is as defined above and described in classes and subclassesherein.

In certain embodiments, a provided pDHA copolymer ispoly(MPEG-b-2-oxypropylene carbonate). In certain embodiments, aprovided pDHA copolymer is poly(MPEG-b-2,2,di(C₁₋₁₂aliphatic)oxy-1,3-propylene carbonate). In certain embodiments, aprovided pDHA copolymer is poly(MPEG-b-2,2,dimethyoxy-1,3-propylenecarbonate).

MPEG-pDHA Copolymer

As described above, the present disclosure provides pDHA copolymers anduses thereof. In some embodiments, provided diblock copolymers comprisemonomethoxy-polyethylene glycol and a polycarbonate based on the humanmetabolite, dihydroxyacetone.

Polyethylene glycol (PEG) based polymers have received considerableattention as biomaterials owing to PEG's favorable chemical andbiological properties, particularly its established biocompatibility andlow immunogenicity (Hubbell, J. A. (1998) “Synthetic biodegradablepolymers for tissue engineering and drug delivery.” Curr Opin Solid StMat Sci 3, 246-251). DHA is a three carbon ketose that is anintermediate metabolite in the glycolysis pathway, making it a promisingbuilding block for new biomaterials (Mathews, C., Van Holde, K. (1996)Biochemistry (The Benjamin/Cummings Publishing Co, Menlo Park, Calif.)).Additionally, DHA is readily manufactured as a fermentative product fromcorn syrup and methanol (Kato, N., Kobayashi, H., Shimao, M., Sakazawa,C. (1986) “Dihydroxyacetone production from methanol by adihydroxyacetone kinase deficient mutant of hansenula-polymorpha.” ApplMicrobiol Biot 23, 180-186). It is currently used as the activeingredient in sunless tanning lotions owing to its ability to formSchiff bases by the reaction of primary amines with its C2 carbonyl(Soler, C., Soley, M. (1993) “Rapid and delayed-effects of epidermalgrowth-factor on gluconeogenesis.” Biochem J 294, 865-872; Davis, L.(1973) “Structure of dihydroxyacetone in solution.” Bioorg Chem 2,197-201; Nguyen, B. C., Kochevar, I. E. (2003) “Influence of hydrationon dihydroxyacetone-induced pigmentation of stratum corneum.” J InvestDermatol 120, 655-661). The DHA-based polycarbonate (pDHA) ishydrophilic, but insoluble in water and most common organic solvents,and is also amendable to one step functionalization through reductiveamination at the C2 carbonyl group (Zelikin, A. N., Zawaneh, P. N.,Putnam, D. (2006) “A functionalizable biomaterial based ondihydroxyacetone, an intermediate of glucose metabolism.”Biomacromolecules 7, 3239-3244).

In certain embodiments, a provided MPEG-pDHA diblock copolymer capturessome of the properties of both its constituting blocks and incorporatesthem to form a physically cross-linked hydrogel upon hydration. Whilenot wishing to be bound by any particular theory, it is believed thatMPEG-pDHA based hydrogels can be injected into the wound bed to act asboth a space filler and bioadhesive owing to pDHA's capacity to bindprimary amines (Zelikin, supra) allowing the gel to hold the tissueflaps together and seal surrounding leaky blood vessels and lymphaticsthereby reducing fluid accumulation.

As described above, the properties and performance of the gel can becontrolled by adjusting the length of the polymer's constituting blocks.Experiments are described in the ensuing Examples wherein MPEG-pDHA issynthesized in various molecular weights (M_(w)). In these particularexperiments, the MPEG M_(w) was held constant at 5000 since, at this lowM_(w), it can undergo renal clearance as required by the FDA forapproved human uses. The pDHA M_(w) was varied (3000, 5000, and 7000) toproduce the three desired block copolymers (abbreviated as 5000-3000,5000-5000, and 5000-7000). MPEG is a water soluble hydrophilic polymer,while pDHA is insoluble in water but hydrophilic based on contact anglemeasurements (Zelikin, supra). These characteristics allow the blockcopolymers to form nanoparticles at low concentrations in aqueousenvironments (Zawaneh, supra). The present disclosure finds unexpectedlythat, at higher polymer concentrations, the block copolymers form gelswith physically entangled networks. While such physical gelation hasbeen observed previously with certain gels of multiblock copolymers inselective solvents (Wang, L. W., Venkatraman, S., Gan, L. H., Kleiner,L. (2005) “Structure formation in injectable poly(lactide-co-glycolide)depots. II. Nature of the gel.” J Biomed Mater Res 72B, 215-222;Nyrkova, I. A., Khokhlov, A. R., Doi, M. (1993) “Microdomains inBlock-Copolymers and Multiplets in Ionomers—Parallels in Behavior.”Macromolecules 26, 3601-3610; He, X. W., Herz, J., Guenet, J. M. (1988)“Physical gelation of a multiblock copolymer—Effect of copolymercomposition.” Macromolecules 21, 1757-1763; He, X. W., Herz, J., Guenet,J. M. (1989) “Physical gelation of a multiblock copolymer—Effect ofsolvent type.” Macromolecules 22, 1390-1397), the processes and/orconditions required to realize hydrogel formation for any givencopolymer are not predictable.

It has been previously observed that an increase in the pDHA chainlength increases the size of the insoluble pDHA domains that form thephysical cross links of the gel, and reduces the relative contributionof the hydrophilic MPEG domain (Wang 2005, supra). While not wishing tobe bound by any particular theory, it is believed that the increasedpDHA chain length subsequently increases the entanglement density, asshown in Example 1, which in turn influences the gel porosity and wateruptake. High water content and increased porosity tend to improve amaterial's biocompatibility, and can also influence its viscosity andelastic nature (Langer, supra).

In certain embodiments, provided MPEG-pDHA gels exhibit a high watercontent that decreases with increasing pDHA chain length andentanglement density, as shown in Table 2 of Example 1. For example, thescanning electron micrographs (SEMs) of cryogenically frozen/lyophilizedgels shown in FIG. 1 also illustrate a high degree of porosity thatdecreases with increasing pDHA chain length and entanglement density.

Two characteristics that may be useful for new biomaterials are the rateof degradation and the composition of the degradation products. Example2 sets forth in vitro degradation studies performed on certain MPEG-pDHAblock copolymers which indicate degradation rates are surprisingly rapidfor a polycarbonate and decrease with increasing pDHA block M. Incertain embodiments, provided copolymers degrade to completion in 24hours (FIG. 3 a). FIG. 3 b is a characteristic ¹H NMR of certain blockcopolymer degradation products, which shows that the soluble polymerdegradation products are MPEG, monomeric DHA, and presumably CO₂ (CO₂ isa common byproduct of polycarbonate degradation) (Tangpasuthadol, V.,Pendharkar, S. M., Kohn, J. (2000) “Hydrolytic degradation oftyrosine-derived polycarbonates, a class of new biomaterials. Part I:Study of model compounds.” Biomaterials 21, 2371-2378; Zhu, K. J.,Hendren, R. W., Jensen, K., Pitt, C. G. (1991) “Synthesis, properties,and biodegradation of poly(1,3-Trimethylene Carbonate).” Macromolecules24, 1736-1740). As a reference, FIG. 11 includes ¹H NMRs of neat MPEGand DHA, respectively. A comparison of FIG. 3 and FIG. 11 shows that the¹H NMR peaks overlap, indicating the degradation products of MPEG-pDHAare MPEG and monomeric DHA.

In addition to these in vitro studies, in vivo studies were performed todetermine the efficacy of pDHA copolymers in the prevention ofpostoperative seroma. As described in Example 3, provided pDHAcopolymers are effective at significantly decreasing mean seroma volumecompared to controls. Given the ease of delivery (injection),compatibility with living tissue and in vivo efficacy, providedcopolymers have been demonstrated to be highly effective surgicalbiomaterials.

Methods of Use

In some embodiments, pDHA copolymers of the present disclosure areprovided for use in medicine. In some embodiments, pDHA copolymers ofthe present disclosure are provided for use in surgery. In certainembodiments, pDHA copolymers of the present disclosure are provided foruse in reconstructive surgery. In certain embodiments, pDHA copolymersof the present disclosure are provided for use in the prevention ofseroma. In some embodiments, the present disclosure provides methods ofusing provided pDHA copolymers to eliminate postoperative dead space andreduce seroma formation.

In some embodiments, the present disclosure provides a method oftreatment comprising administering a material comprising apoly-dihydroxyacetone (pDHA) copolymer at or near a wound bed orsurgical site of a patient. In certain embodiments, the presentdisclosure provides a method for the prevention or treatment of seromas,the method comprising the step of: administering a material comprising apoly-dihydroxyacetone (pDHA) copolymer at or near a wound bed orsurgical site. In certain embodiments, the wound bed or surgical site isin the abdomen.

Seromas

A seroma is an abnormal collection of serous fluid within the tissues ofthe body, akin to an internal blister. Postoperative accumulations ofserous fluid are frequently encountered in patients, particularly when asurgical procedure has required the loosening of relatively large flapsof skin from underlying subcutaneous tissue and deep fascia (e.g.,ablative and reconstructive surgeries). Surgeries that require extensivetissue dissection and create large empty spaces can disrupt normallymphatic flow. Subsequently, transduate fluid collects in these poorlydrained “dead spaces” resulting in formation of a seroma (Agrawal, A.,Ayantunde, A. A., Cheung, K. L. (2006) “Concepts of seroma formation andprevention in breast cancer surgery.” ANZ J Surg 76, 1088-1095; Kuroi,K., et al. (2005) “Pathophysiology of seroma in breast cancer.” BreastCancer 12, 288-293). Seromas can lead to significant patient morbiditysuch as infection, decreased limb mobility, and re-operation (Agrawal,supra; Schwabegger, A., Ninkovic, M., Brenner, E., Anderl, H. (1997)“Seroma as a common donor site morbidity after harvesting the latissimusdorsi flap: Observations on cause and prevention.” Ann Plas Surg 38,594-597; Budd, D. C., Cochran, R. C., Sturtz, D. L., Fouty, W. J. (1978)“Surgical morbidity after mastectomy operations.” Am J Surg 135,218-220). Seroma formation rates range from 9.1 to 81%, depending on thenature of the surgical procedure (Schwabegger, supra; Woodworth, P. A.,McBoyle, M. F., Helmer, S. D., Beamer, R. L. (2000) “Seroma formationafter breast cancer surgery: Incidence and predicting factors.” Am Surg66, 444-450; Roses, D. F., Brooks, A. D., Harris, M. N., Shapiro, R. L.,Mitnick, J. (1999) “Complications of level I and II axillary dissectionin the treatment of carcinoma of the breast.” Ann Surg 230, 194-201;Abe, M., Iwase, T., Takeuchi T., Murai H., Miura S. (1998) “A randomizedcontrolled trial on the prevention of seroma after partial or totalmastectomy and axillary lymph node dissection.” Breast Cancer 5, 67-69;Say, C. C., Donegan, W. (1974) “Biostatistical evaluation ofcomplications from mastectomy.” Surg Gynecol Obstet 138, 370-376;Alvandi, R. Y., Solomon, M. J., Renwick, S. B., Donovan, J. K. (1991)“Preliminary results of conservative treatment of early breast cancerwith axillary dissection and post operative radiotherapy. Aretrospective review of 107 patients.” Aust N Z J Surg 9, 670-674;Osteen, R. T., Karnell, L. H. (1994) “The national cancer data-basereport on breast-cancer.” Cancer 73, 1994-2000). Notably, modifiedradical mastectomies lead to seroma formation rates ranging from 15 to38.6%, while radical mastectomies report a rate as high as 52% (Budd,supra; Hayes, J. A., Bryan, R. M. (1984) “Wound-healing followingmastectomy.” Aust N Z J Surg 54, 25-27; Aitken, D. R., Hunsaker, R.,James, A. G. (1984) “Prevention of seromas following mastectomy andaxillary dissection.” Surg Gynecol Obstet 158, 327-330; Chilson, T. R.,Chan, F. D., Lonser, R. R., Wu, T. M., Aitken, D. R. (1992) “Seromaprevention after modified radical-mastectomy.” Am Surg 58, 750-754;Terrell, G. S., Singer, J. A. (1992) “Axillary versus combined axillaryand pectoral drainage after modified radical-mastectomy.” Surg GynecolObstet 175, 437-440).

As an example, in the course of performing a radical mastectomy, thesurgeon removes substantially all of the patient's breast tissue betweenthe rib cage and a relatively large area of overlying skin. Followingsurgery, it is necessary for the resulting relatively large flap of skinto heal with and adhere to the underlying tissue. However, anaccumulation of serous fluid tends to collect between the overlying skinflap and the underlying tissue. This collection of serious fluid tendsto prevent the skin from healing with the subcutaneous tissue and deepfascia, and also provides a medium highly susceptible to infection.

In current clinical practice, silicone surgical drains are placed in thewound bed through separate stab incisions to collect transudate fluidbut they can be a significant source of pain and discomfort to patients,especially upon their removal up to several weeks after the initialsurgical procedure. Furthermore, these procedures can further increasethe risk of infection at the surgical site.

Provided pDHA copolymers can be used to treat and prevent seromasresulting from a variety of surgical procedures. Such proceduresinclude, without limitation, cancer resection and general surgeryprocedures such as mastectomies, lumpectomies, embolectomies; lipomaexcisions, hysterectomies, plastic surgery procedures such asabdominoplasties, forehead lifts, buttocks lifts, face lifts,liposuction, skin grafts, implant surgery (e.g., calf, bicep, tricep,pectoral, penile, subdermal, transdermal, dental, bone), rhytidectomiesor rhinoplasties; mammaplasties; biopsy closure, cleft-palatereconstruction, incidional hernia repair, lymph node resection, groinrepair, Caesarean section, laparoscopic trocar repair, vaginal tearrepair, orthopedic procedures, laminectomies, treatment of traumaticlesions, fistula treatment, graft fixation, nerve repair, electrocauteryprocedures, resection of the thyroid or parathyroid glands, dentalprocedures such as tooth extraction, and hand surgery. Provided pDHAcopolymers are also useful in the treatment and prevention of seromasthat may result from veterinary surgical procedures.

Tissue Adhesion

Provided pDHA copolymers are useful in the prevention of postoperativetissue adhesion. Adhesions which may be formed include the adhesion oftissue to tissue or of tissue to bone. As generally known, theoccurrence of post-operative adhesion formation after internal surgeryis a major problem in abdominal surgery. For example, tissue adhesioncomplications may affect fertility in gynecological patients. Becauseadhesions occur in about 70% of the gynecological abdominal surgicalinterventions, it is evident that there is a need for a suitable methodfor preventing the above-identified adhesions, and the complications andpatient discomfort associated therewith.

It has been known to separate adjacent internal bodily surfaces byinterposing a mesh or film so that during tissue regeneration followingsurgery no contact exists between the surfaces. One material which hasbeen employed to prevent adhesions is an expandedpolytetrafluoroethylene material known as Gore-Tex®. This material,however, is not hemostatic and is non-degradable by the human body. Thusthe implant remains in the body, and, if necessary, must be removedsurgically following the healing process. Another material is a meshbarrier of carboxymethylcellulose known as Interceed®. This material,however, may not be applied in a blood-rich environment as under suchcircumstances the material quickly loses its barrier function. Othershave disclosed firms of poly(ethyleneoxide) and polyethyleneterephthalate as barrier materials to prevent surgical adhesions(Gilding and Reed, in Polymer, Vol. 20 pgs. 1454-1458 (December 1979)and in Polymer, Vol. 22, pgs. 499-504 (April 1981).

The present disclosure provides a method for the prevention or treatmentof post-operative tissue adhesion, the method comprising the step of:administering a material comprising a poly-dihydroxyacetone copolymer ator near a wound bed or surgical site. The present disclosure alsoprovides a method for achieving hemostasis, the method comprising thestep of: administering a material comprising a poly-dihydroxyacetone(pDHA) copolymer at or near a wound bed or surgical site.

Hemostasis

The present disclosure provides a method for achieving hemostasis, themethod comprising the step of: administering a material comprising apoly-dihydroxyacetone (pDHA) copolymer at or near a wound bed orsurgical site. In certain embodiments, the wound bed or surgical sitecomprises a hepatic surface. In certain embodiments, the step ofadministering a material comprising a poly-dihydroxyacetone (pDHA)copolymer comprises dusting the material onto the bleeding surface.

In certain embodiments, the methods described herein are palliative withrespect to the conditions being treated. In certain embodiments, themethods are preventative. In certain embodiments, the methods arecurative.

The present disclosure provides “pharmaceutically acceptable”compositions, which comprise a therapeutically effective amount of oneor more of the compounds described herein, formulated together with oneor more pharmaceutically acceptable carriers (additives) and/ordiluents. As described in detail, the pharmaceutical compositions of thepresent disclosure may be specially formulated for administration insolid or liquid form, including those adapted for the following:parenteral administration, for example, by subcutaneous, intramuscular,intravenous or epidural injection as, for example, a sterile solution orsuspension; topical application, for example, as a cream, ointment, or acontrolled-release patch.

The present disclosure further provides kits comprising compositions ofpDHA copolymers. The kit optionally includes instructions for preparingand/or administering a provided composition. In certain embodiments, thekit includes multiple doses of the composition. In certain embodiments,the kit includes additional components or tools useful for thepreparation and/or administration of a composition. The kit may includesufficient quantities of each component to treat a subject for a week,two weeks, three weeks, four weeks, or multiple months.

EXAMPLES

In addition to those described herein, methods of preparingpoly-dihydroxyacetone and derivatives thereof are described in U.S.Patent Publication No. 2008/0194786, the entire contents of which arehereby incorporated by reference.

General Procedures

Monomethoxy-poly(ethylene glycol) (MPEG) (M_(w) 5000) was purchased fromPolysciences (Warrington, Pa.). Prior to use, MPEG was dried byazeotropic distillation in toluene. Dihydroxyacetone dimer (DHA),p-toluene sulfonic acid, trimethyl orthoformate, Sn(Oct)₂, ethylchloroformate, and 5% phosphotungstic acid were purchased fromSigma-Aldrich (St. Louis, Mo.) and used as received. Triethylamine,tetrahydrofuran (THF), dichloromethane (CH₂Cl₂), diethyl ether,methanol, toluene, and TFA were purchased from VWR (West Chester, Pa.)and used as received. Syringes and PBS (pH 7.4) were purchased fromFisher Scientific. Collagen was purchased from MP Biomedicals.

¹H NMR spectra were recorded on a Mercury 300 spectrometer. Gelpermeation chromatography (GPC) was carried out using PSS SDV columns500A, 50A, and linear M (in series) with a THF mobile phase (1 ml/min)and polystyrene standards with UV (Waters 486) and RI (Waters 2410)detection. Rheology measurements were performed using a Physica ModularCompact 300 Rheometer. Scanning Electron Microscopy (SEM) measurementswere performed using the LEICA 440.

The swelling degree (S.D.) of provided polymers was obtained byhydrating 30 mg of each MPEG-pDHA molecular weight (n=4) in 1.0 mL ofPBS at room temperature. The gels were allowed to sit for approximately4 minutes on a filter paper to drain the excess PBS. The gels wereweighed to obtain the swollen weight (W_(s)), then lyophilized andweighed again to obtain the dry weight (W_(d)). S.D. was calculatedusing equation 1 (Barbucci, R., Rappuoli, R., Borzacchiello, A.,Ambrosio, L. (2000) “Synthesis, chemical and rheologicalcharacterization of new hyaluronic acid-based hydrogels.” J BiomatSci-Polym E 11, 383-399):

S.D. (%)=(Ws/Wd)*100  (1)

Rheological tests were performed using a Physica Modular Compact 300using parallel plate geometry (8 mm diameter parallel plate). Data wasrecorded using US200 software and analyzed using an Excel spreadsheet.All experiments were performed at 28 and 37° C. The viscoelasticproperties of the gels were determined by performing frequency sweepexperiments in the oscillatory mode with a 1% strain amplitude andfrequency range of 0.1-100 l/s. Step stain experiments, with a 1%strain, were performed to determine the stress relaxation of the gels.

Entanglement density was calculated using the plateau storage modulus,G_(e) (the maximum G′ where G′/G″>1) (Rubinstein, M., Colby, R. (2003)Polymer Physics (Oxford University Press, NYC); Macosko, C. W. (1994)Rheology: Principles, Measurements, and Applications (VCH Publishers,NYC). Using Equation 2:

G _(e) =σkT  (2)

wherein:

G_(e) is the plateau G′,

ν is the entanglement density (m⁻³),

k is the Boltzman constant (kg·m²·s⁻²·K⁻), and

T is the temperature (K).

Calculation of the chain relaxation time (τ) was obtained my measuringthe relaxation modulus (G(t)) following a small step strain (as shown inFIG. 10). Using equation 3 (Rubinstein and Macosko, supra).

G(t)=G(τ)exp^(−t/τ)  (3)

wherein:

G(t) is the relaxation modulus (Pa),

G(τ) is constant (Pa),

t is time (s), and

τ is the chain relaxation time (s).

Differentiating and rearranging equation (3) yields:

$\begin{matrix}{\left\lbrack {{tG}(t)} \right\rbrack^{\prime} = {G\; {\exp^{- {(\frac{t}{\tau})}}\left( {1 - \frac{t}{\tau}} \right)}}} & (4)\end{matrix}$

Using equation 4, a plot of tG(t) vs. t yields a plot with a maximum att=r, which is the chain relaxation time (τ).

Example 1 Polymer Synthesis

Poly(MPEG-b-2-oxypropylene carbonate) (VII) (MPEG-pDHA) was synthesizedusing a previously published protocol (Zawaneh, supra). Briefly,dihydroxyacetone dimer (II) was locked in its monomeric form byconversion of its C2 carbonyl group into a dimethoxy acetal usingtrimethyl-orthoformate and p-toluenesulfonic acid (III) (See FIG. 6).This was then converted to a 6-membered cyclic carbonate (IV). IV waspolymerized using Sn(Oct)₂ in the presence of monomethoxy poly(ethyleneglycol) (MPEG) to form (VI). The molecular weight of the MPEG was fixedat 5000, while the molecular weight of the DHA based polymer chain wasvaried depending on the reactant feed ratios and the Sn(Oct)₂ injectionconditions (molecular weights of 3000, 5000, 7000, and 10000 weresynthesized). This polymer was subsequently deprotected using aTFA-water mixture (4:1) to produce the desired polymer, MPEG-pDHA (VII).The amount of TFA-water needed to deprotect the polymer depended on thelength of the pDHA based segment. Table 1 summarizes the polymerizationconditions used to synthesize each molecular weight. The reaction schemeis also shown in FIG. 6. MPEG-pDHA ¹H NMR (DMSO-d₆) δ: 5.00 (s; 4H),3.50 (s; 4H), 3.24 (s; 3H).

TABLE 1 Summary of the polymerization and deprotection conditions used.Sn(Oct)₂ MPEG IV injection feed feed Sn(Oct)₂ temp TFA-H₂O: VI MPEG-pDHA(mg) (mg) (μL) (° C.) (mL/100 mg) 5000-3000 550 470 10 25 0.92 5000-5000250 420 10 100 1.30 5000-7000 150 420 8 100 1.50  5000-10000 100 520 8100 1.80

TABLE 2 Summary of selected MPEG-pDHA gel swelling measurements, crosslink density, and chain relaxation times following shear. Increasing thepDHA chain length reduces the extent of swelling and increases thehydrogel cross link density and relaxation time. Weight gain Sampleswelling Entanglement density Relaxation time MPEG-pDHA (%) ν (m⁻³) τ(s) 5000-3000 587.5 ± 18.3 4.96e24 250 5000-5000 513.1 ± 12.2 1.48e25250 5000-7000 396.0 ± 22.3 3.25e25 350

Hydrogel Characterization

In some embodiments, MPEG-pDHA hydrogels are thixotropic and exhibit atrend of decreasing viscosities with increasing shear rates (FIG. 2 a).This thixotropic nature allows hydrogels to form extrudable materialsthat can be delivered (e.g., to a seroma) by injection even at remotesites. An increase in pDHA chain length and subsequent increase inentanglement density lead to an increase in hydrogel viscosity (FIG. 2a). FIG. 2 b illustrates an example of MPEG-pDHA 5000-5000 uponextrusion from a narrow-bore 26 G hypodermic needle. A complete set ofviscosity measurements at 28° C. and 37° C. is provided in FIG. 7.

In certain embodiments, controlling a hydrogel's entanglement density isuseful for controlling its viscosity and porosity. Entanglementdensities are calculated from the storage (G′) and loss (G″) modulimeasurements (as detailed above), which also provide insight into theelastic nature of the gels. FIG. 2 c is an example of a typical G′ andG″ graph as obtained for an MPEG-pDHA hydrogel (5000-3000 and5000-7000). The G′ values display very low frequency dependence and aregreater than G″ values across the entire frequency range, a trendcharacteristic of elastic hydrogels (Vermonden, T., Besseling, N. A. M.,van Steenbergen, M. J., Hennink, W. E. (2006) “Rheological studies ofthermosensitive triblock copolymer hydrogels.” Langmuir 22, 10180-10184;Nowak, A. P., et al. (2002) “Rapidly recovering hydrogel scaffolds fromself-assembling diblock copolypeptide amphiphiles.” Nature 417,424-428). The G′ and G″ values also increase with increasing pDHA chainlength and entanglement density. A complete set of G′ and G″measurements is provided in FIGS. 8 and 9.

MPEG-pDHA chain relaxation time was calculated from the rheologicaldata. Relaxation calculations help determine the hydrogel relaxationkinetics following a step strain, which can provide insight into howlong it takes the MPEG-pDHA hydrogel chains to relax to theirequilibrium state following injection at the seroma site. Rapidrelaxation times help ensure that a biomaterial rapidly reverts to itsequilibrium state, and subsequently reduce the number of variables thatcan influence the performance of a therapeutic hydrogel in vivo. In someembodiments, MPEG-pDHA gels display rapid relaxation times (250-350 s)which also increase with increasing pDHA chain length and entanglementdensity (See Table 2) (Sahiner, N., Singh, M., De Kee, D., John, V. T.,McPherson, G. L. (2006) “Rheological characterization of a chargedcationic hydrogel network across the gelation boundary.” Polymer 47,1124-1131). Equations that were used to calculate MPEG-pDHA hydrogelrelaxation times are shown above. A complete set of chain relaxationdata is provided in FIG. 10 and Table 3.

TABLE 3 Relaxation times of MPEG-pDHA. The relaxation times increasewith increasing pDHA chain length. MPEG-pDHA τ (s) at 28° C. τ (s) at37° C. 5000-3000 250 250 5000-5000 250 250 5000-7000 350 300

Example 2 In Vitro Hydrolytic Degradation

In vitro degradation studies were performed on MPEG-pDHA 5000-3000,5000-5000, and 5000-7000. The polymer samples were weighed out into 20mg samples and placed in 1.0 mL PBS (pH=7.4) 1.5 mL Eppendorf tubes. Thesamples were placed on an orbital shaker and incubated at 37° C. Sampleswere recovered for each polymer at the selected time points (n=3). Thesamples were recovered, washed with DI water, lyophilized, andre-weighed. Degradation products from fully degraded samples werecharacterized by ¹H NMR. ¹H NMR (D₂O) DHA δ: 4.40 (s; 4H), 3.55 (s; 6H).¹H MPEG (D₂O) DHA δ: 3.70 (s; 4H).

Example 3 Anti-Seroma Efficacy (In Vivo)

Following the rheological and degradation characterization of MPEG-pDHA,we evaluated how hydrogels performed in a potential surgicalapplication, the prevention of postoperative seroma. A well-establishedrat mastectomy model was used to determine the efficacy of MPEG-pDHA,and to allow direct comparison to the literature (Silverman, supra). Asshown in FIG. 4, the untreated controls displayed a mean seroma volumeof 2.28±0.55 mL, whereas MPEG-pDHA 5000-3000 treated rats displayed asignificantly decreased mean seroma volume of 0.044±0.017 mL (p<0.01).Interestingly, MPEG-pDHA 5000-5000 and 5000-7000 treated rats displayeda mean seroma volume of 2.53±0.70 (p=0.8) and 1.93±0.60 (p=0.2),respectively which are statistically equivalent to the untreated controlanimals. Post-mortem examination of animals treated with MPEG-pDHA5000-3000 demonstrated gross fibrinous adhesions between the elevatedskin flap and chest wall whereas no adhesions were evident in the othertreatment or control groups. In vivo degradation of the polymer wasconfirmed by the absence of residual polymer (all three compositions)upon histological examination of excised tissue from the wound bed atseven days after application. At day 1 post surgery residual MPEG-pDHAwas evident (FIG. 12), suggesting the in vivo rate of degradation isslower than observed in vitro, however, no residual polymer wasvisualized on day 3 (FIG. 13).

With respect to biocompatibility, there was normal-appearing earlygranulation tissue and a mild inflammatory response that was equal tountreated control animals (FIG. 5). These results suggest that MPEG-pDHAand its degradation products are well tolerated by the soft tissuesurrounding the wound bed and do not negatively impact the normalsequence of early wound healing.

Experimental

To evaluate the efficacy of the polymer gels, each MPEG-pDHA based gelwas evaluated in a well established rat model of seroma formation(Lindsey, supra). Briefly, following a midline incision, a skin flap wasraised over the right chest, exposing the right pectorals major musclewhich was then excised. A right axillary lymphadenctomy was thenperformed under an operating microscope. The fully hydrated hydrogel wasprepared freshly to full hydration by mixing 100 mg of lyophilizedMPEG-pDHA powder with sterile saline over filter paper. Experimentalrats received 0.5 cc of MPEG-pDHA hydrogel into the wound bed beforeclosure while controls received 0.5 cc of saline into the wound bedbefore closure.

Animals were sacrificed on post operative day seven by carbon dioxideasphyxiation followed by cervical dislocation as per institutionalguidelines approved for such investigation. Seroma fluid was aspiratedpercutaneously via an 18 gauge needle and measured volumetrically. Theincision site was then opened and any remaining seroma fluid was removedby needle aspiration. To determine in vivo biocompatibility of thepolymer, sections of the skin flap and the underlying wound bed wereremoved en bloc and analyzed histologically (H+E stain) for evidence ofresidual polymer and inflammation in the area of application. A studenttwo tail t-test with unequal variance was performed to determine the pvalue (α=0.05).

Example 4

To make a correlation between anti-seroma efficacy and the polymerstructure, we conducted three mechanism-oriented experiments. First, wedegraded MPEG-pDHA 5000-3000 in water into oligomeric products toascertain whether the polymer degradation products were a causativefactor in seroma prevention. As shown in FIG. 4, hydrolyzed MPEG-pDHAwas ineffective, suggesting the full length polymer upon administrationis necessary for anti-seroma activity. Second, the MPEG-pDHA hydrogelwas hydrated in the presence of a 2-fold mole excess of lysine (relativeto C2 carbonyl groups) to determine whether the C2 carbonyl reactivitywith the primary amines in the tissue was necessary for anti-seromaactivity. The lysine was added to occupy the C2 carbonyl groups,therefore, if C2 reactivity with the amines in the tissue is necessaryfor activity, the lysine-hydrated formulation should be less active. Asshown in FIG. 4, although the lysine-hydrated formulation showed areduced seroma volume, the reduction was statistically equivalent to thecontrol, suggesting that the reactivity of the C2 carbonyl takes part inpreventing seroma. Third, to determine if MPEG-pDHA initiated theclotting cascade to facilitate tissue integration, we measured theeffect of the polymer on prothrombin time (PT) and partialthromboplastin time (PTT). The results show that the biomaterial has noeffect on PT and PTT suggesting that activation of the clotting cascadeis not a factor in seroma prevention. Additional details, includingexperiments describing the hemostatic efficacy of provided copolymers,are described by Henderson, P. W., et al. (2009) “A rapidly resorbablehemostatic biomaterial based on dihydroxyacetone.” Journal of BiomedicalMaterials Research Part A. DOI: 10.1002/jbm.a.32586), the entirecontents of which is incorporated by reference.

While we have described a number of embodiments of this invention, it isapparent that our basic examples may be altered to provide otherembodiments that utilize the compounds and methods of this invention.Therefore, it will be appreciated that the scope of this invention is tobe defined by the appended claims rather than by the specificembodiments that have been represented by way of example.

1-42. (canceled)
 43. A copolymer comprising poly-dihydroxyacetone(pDHA), wherein the copolymer is a cross-linked hydrogel.
 44. Thecopolymer of claim 43, wherein the cross-linked hydrogel is physicallycrosslinked.
 45. The copolymer of claim 43, wherein the copolymer isthixotropic. 46-48. (canceled)
 49. The copolymer of claim 43, whereinthe pDHA copolymer is a copolymer of DHA and a polyol.
 50. The copolymerof claim 43, wherein the pDHA copolymer is a copolymer of DHA andalkylene glycol. 51-52. (canceled)
 53. The copolymer of claim 43,wherein the pDHA copolymer is a PEG-pDHA diblock copolymer. 54-67.(canceled)
 68. The copolymer of claim 53, wherein the alkylene glycolblock is terminated with a suitable organic group.
 69. The copolymer ofclaim 68, wherein the organic group is aliphatic, acyl, heteroaliphatic,aryl, or heteroaryl.
 70. The copolymer of claim 68, wherein the organicgroup is selected from the group consisting of carbohydrates, proteins,and peptides.
 71. The copolymer of claim 69, wherein the organic groupis monomethoxy.
 72. The copolymer of claim 43, wherein the pDHA polymeris poly(MPEG-b-2-oxypropylene carbonate).
 73. The copolymer of claim 43,wherein the pDHA polymer is poly(MPEG-b-2,2,di(C₁₋₁₂aliphatic)oxy-1,3-propylene carbonate).
 74. The copolymer of claim 73,wherein the pDHA polymer is poly(MPEG-b-2,2,dimethyoxy-1,3-propylenecarbonate).
 75. The copolymer of claim 43, wherein the copolymer is offormula VII-a:

wherein, R¹ and R² are each independently an optionally substitutedgroup selected from C₁₋₂₀ aliphatic; a 3- to 7-membered saturated orpartially unsaturated monocyclic carbocyclic ring; a 7- to 10-memberedsaturated or partially unsaturated bicyclic carbocyclic ring; phenyl; an8- to 10-membered bicyclic aryl ring; a 3- to 7-membered saturated orpartially unsaturated monocyclic heterocyclic ring having 1-2heteroatoms independently selected from nitrogen, oxygen, or sulfur; a7- to 10-membered saturated or partially unsaturated bicyclicheterocyclic ring having 1-3 heteroatoms independently selected fromnitrogen, oxygen, or sulfur; an 8- to 10-membered bicyclic aryl ring; a5- to 6-membered heteroaryl ring having 1-3 heteroatoms independentlyselected from nitrogen, oxygen, or sulfur; or an 8- to 10-memberedbicyclic heteroaryl ring having 1-4 heteroatoms independently selectedfrom nitrogen, oxygen, or sulfur; and n and m each independently rangefrom 1 to
 2000. 76. The copolymer of claim 43, wherein the copolymer isof formula VIII:

wherein each of R¹, R², n, and m is as defined above and described inclasses and subclasses herein, and R³ and R⁴ are each independentlyselected from the group consisting of R⁵, —OR⁵, and —N(R⁵)₂; or: R³ andR⁴ are optionally taken together with their intervening atoms to form anoptionally substituted ring selected from a 3- to 7-membered saturatedor partially unsaturated monocyclic heterocyclic ring having 1-2heteroatoms independently selected from nitrogen, oxygen, or sulfur; ora 7- to 10-membered saturated or partially unsaturated bicyclicheterocyclic ring having 1-3 heteroatoms independently selected fromnitrogen, oxygen, or sulfur; and each R⁵ is independently hydrogen or anoptionally substituted group selected from C₁₋₂₀ aliphatic; a 3- to7-membered saturated or partially unsaturated monocyclic carbocyclicring; a 7- to 10-membered saturated or partially unsaturated bicycliccarbocyclic ring; phenyl; an 8- to 10-membered bicyclic aryl ring; a 3-to 7-membered saturated or partially unsaturated monocyclic heterocyclicring having 1-2 heteroatoms independently selected from nitrogen,oxygen, or sulfur; a 7- to 10-membered saturated or partiallyunsaturated bicyclic heterocyclic ring having 1-3 heteroatomsindependently selected from nitrogen, oxygen, or sulfur; an 8- to10-membered bicyclic aryl ring; a 5- to 6-membered heteroaryl ringhaving 1-3 heteroatoms independently selected from nitrogen, oxygen, orsulfur; or an 8- to 10-membered bicyclic heteroaryl ring having 1-4heteroatoms independently selected from nitrogen, oxygen, or sulfur. 77.A copolymer comprising DHA and glycerol. 78-79. (canceled)
 80. Thecopolymer of claim 77, comprising a first block of PEG; and a secondblock of polymer comprising DHA and glycerol. 81-82. (canceled)
 83. Thecopolymer of claim 77, comprising DHA, glycerol, and PEG. 84-85.(canceled)
 86. The copolymer of claim 43 comprising a repeating subunit:

wherein: R³ and R⁴ are each independently selected from the groupconsisting of R⁵, —OR⁵, and —N(R⁵)₂; or: R³ and R⁴ are optionally takentogether with their intervening atoms to form an optionally substitutedring selected from a 3- to 7-membered saturated or partially unsaturatedmonocyclic heterocyclic ring having 1-2 heteroatoms independentlyselected from nitrogen, oxygen, or sulfur; or a 7- to 10-memberedsaturated or partially unsaturated bicyclic heterocyclic ring having 1-3heteroatoms independently selected from nitrogen, oxygen, or sulfur; andeach R⁵ is independently hydrogen or an optionally substituted groupselected from C₁₋₂₀ aliphatic; a 3- to 7-membered saturated or partiallyunsaturated monocyclic carbocyclic ring; a 7- to 10-membered saturatedor partially unsaturated bicyclic carbocyclic ring; phenyl; an 8- to10-membered bicyclic aryl ring; a 3- to 7-membered saturated orpartially unsaturated monocyclic heterocyclic ring having 1-2heteroatoms independently selected from nitrogen, oxygen, or sulfur; a7- to 10-membered saturated or partially unsaturated bicyclicheterocyclic ring having 1-3 heteroatoms independently selected fromnitrogen, oxygen, or sulfur; an 8- to 10-membered bicyclic aryl ring; a5- to 6-membered heteroaryl ring having 1-3 heteroatoms independentlyselected from nitrogen, oxygen, or sulfur; or an 8- to 10-memberedbicyclic heteroaryl ring having 1-4 heteroatoms independently selectedfrom nitrogen, oxygen, or sulfur.
 87. The copolymer of claim 86, whereinthe copolymer is of formula VIII:

wherein: R¹ and R² are each independently an optionally substitutedgroup selected from C₁₋₂₀ aliphatic; a 3- to 7-membered saturated orpartially unsaturated monocyclic carbocyclic ring; a 7- to 10-memberedsaturated or partially unsaturated bicyclic carbocyclic ring; phenyl; an8- to 10-membered bicyclic aryl ring; a 3- to 7-membered saturated orpartially unsaturated monocyclic heterocyclic ring having 1-2heteroatoms independently selected from nitrogen, oxygen, or sulfur; a7- to 10-membered saturated or partially unsaturated bicyclicheterocyclic ring having 1-3 heteroatoms independently selected fromnitrogen, oxygen, or sulfur; an 8- to 10-membered bicyclic aryl ring; a5- to 6-membered heteroaryl ring having 1-3 heteroatoms independentlyselected from nitrogen, oxygen, or sulfur; or an 8- to 10-memberedbicyclic heteroaryl ring having 1-4 heteroatoms independently selectedfrom nitrogen, oxygen, or sulfur; and n and m each independently rangefrom 1 to 2000.